Fishes

15 pages, 10154 KiB

Open AccessFeature PaperArticle

Selection of Reference Gene for Expression Studies in the Ovary and Pituitary of Spotted Scat (Scatophagus argus) at Different Ovarian Stages

by Zhilong Liu, Tuo Wang, Peng Liu, Dongneng Jiang, Xi Liu, Siping Deng, Tianli Wu, Yang Huang, Chunhua Zhu, Guangli Li and Mouyan Jiang

Fishes 2023, 8(2), 120; https://doi.org/10.3390/fishes8020120 - 20 Feb 2023

Viewed by 1384

Abstract

The spotted scat (Scatophagus argus) is the most widely commercially cultured fish in eastern and southern Asia that possess potential economic value. However, up to date, there are no studies reported on the selection of suitable reference genes in this fish, [...] Read more.

The spotted scat (Scatophagus argus) is the most widely commercially cultured fish in eastern and southern Asia that possess potential economic value. However, up to date, there are no studies reported on the selection of suitable reference genes in this fish, which is crucial for guaranteeing accurate and reliable results in RT-qPCR analyses. This study aimed at screening the most stable reference genes in the ovary and pituitary at different ovarian stages, which is of great significance for further research on the reproductive regulation mechanism of female S. argus. In this study, we selected twenty-one genes as the candidate reference genes, including four genes in the ovary (EEF1A, ACTB, B2M, and HPRT1), and seventeen genes in the pituitary (B2M, APOA1, CGBA, RPLP0, GNRHR, GUSB, TBP, SLC25A5, RPL4, PLA1A, GAPDH, GNB2L1, CTFS, HPRT1, RPS2, TFRC, and TUBB4B). To analyze the stability of the potential reference genes, we first used four commonly used software, BestKeeper, GeNorm, NormFinder, and ΔCt, and then we established comprehensive rankings with ReFinder. The results indicate that RPL4 and GNB2L1, and EEF1A and HPRT1 were the most appropriate reference genes for the pituitary and ovary of S. argus, respectively, in the three developmental stages of the ovary. Additionally, GeNorm analysis suggested that for the accurate normalization of gene expression, two reference genes were reliable in the ovary and pituitary of S. argus. To the best of our knowledge and understanding, this is the first study to identify appropriate reference genes for analyzing gene expression in S. argus. Consequently, this study can be used as a foundation for future research on the reproduction of S. argus. Full article

(This article belongs to the Section Physiology and Biochemistry)

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14 pages, 2564 KiB

Open AccessArticle

The “True Colours” of Golden Loaches (Teleostei: Cobitidae)

by Jakub Fedorčák, Radek Šanda, Tihomir Stefanov, Jan Mendel, Michal Nowak, Peter Križek, Anabel Perdices, Jasna Vukić and Ján Koščo

Fishes 2023, 8(2), 119; https://doi.org/10.3390/fishes8020119 - 20 Feb 2023

Viewed by 1756

Abstract

Loaches of the genus Sabanejewia are model organisms for many ichthyologic studies focusing on morphological and colour variation. The bright lateral spots—a part of the mimicry of this fish—cause a taxonomic puzzle. Common practice is that morphometric and molecular studies lack habitat assessments [...] Read more.

Loaches of the genus Sabanejewia are model organisms for many ichthyologic studies focusing on morphological and colour variation. The bright lateral spots—a part of the mimicry of this fish—cause a taxonomic puzzle. Common practice is that morphometric and molecular studies lack habitat assessments of species originating from different environments. In this study, we analysed body shape and colour variation within two species of Sabanejewia in order to reveal whether they are more affected by phylogeny or environmental conditions. The environmental parameters were obtained using satellite mapping tools, body shape using geometric morphometry, and the molecular identification of specimens using an analysis of mitochondrial DNA (sequence of the cytochrome b gene). Generalized linear mixed models were used for the analysis of lateral spot numbers, and principal components analysis to describe the changes in landmark position defined by the permutation tests. Results show a significant impact of the locality elevation and specimen’s sex on the change of the body shape. We identified significant differences in the number of lateral spots, which are considered mimicry variation across an elevation gradient. Morphological differences of Sabanejewia spp. vary with ecological factors along the river continuum. Full article

(This article belongs to the Section Biology and Ecology)

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12 pages, 2577 KiB

Open AccessArticle

CRISPR/Cas9-Mediated Disruption of Endo16 Cis-Regulatory Elements in Sea Urchin Embryos

by Lili Xing, Lingyu Wang, Femke Roos, Michelle Lee and Gregory A. Wray

Fishes 2023, 8(2), 118; https://doi.org/10.3390/fishes8020118 - 20 Feb 2023

Viewed by 1664

Abstract

Sea urchins have become significant mariculture species globally, and also serve as invertebrate model organisms in developmental biology. Cis-regulatory elements (enhancers) control development and physiology by regulating gene expression. Mutations that affect the function of these sequences may contribute to phenotypic diversity. Cis-regulatory [...] Read more.

Sea urchins have become significant mariculture species globally, and also serve as invertebrate model organisms in developmental biology. Cis-regulatory elements (enhancers) control development and physiology by regulating gene expression. Mutations that affect the function of these sequences may contribute to phenotypic diversity. Cis-regulatory targets offer new breeding potential for the future. Here, we use the CRISPR/Cas9 system to disrupt an enhancer of Endo16 in developing Lytechinus variegatus embryos, in consideration of the thorough research on Endo16’s regulatory region. We designed six gRNAs against Endo16 Module A (the most proximal region of regulatory sequences, which activates transcription in the vegetal plate and archenteron, specifically) and discovered that Endo16 Module A-disrupted embryos failed to undergo gastrulation at 20 h post fertilization. This result partly phenocopies morpholino knockdowns of Endo16. Moreover, we conducted qPCR and clone sequencing experiments to verify these results. Although mutations were not found regularly from sequencing affected individuals, we discuss some potential causes. In conclusion, our study provides a feasible and informative method for studying the function of cis-regulatory elements in sea urchins, and contributes to echinoderm precision breeding technology innovation and aquaculture industry development. Full article

(This article belongs to the Special Issue The Applications of Genome Editing and Genomics in Aquaculture)

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14 pages, 2464 KiB

Open AccessArticle

Exploitation and Conservation Status of the Thornback Ray (Raja clavata) in the Balearic Islands (Western Mediterranean)

by Francesca Ferragut-Perello, Sergio Ramírez-Amaro, Athanassios C. Tsikliras, Natalia Petit-Marty, Donna Dimarchopoulou, Enric Massutí, Alba Serrat and Francesc Ordines

Fishes 2023, 8(2), 117; https://doi.org/10.3390/fishes8020117 - 19 Feb 2023

Cited by 1 | Viewed by 2170

Abstract

Fisheries management requires the best scientific knowledge on the exploitation and conservation status of stocks. This is challenging for by-catch species, for which necessary data for their assessment is more limited than for target ones. That is the case for the thornback ray, [...] Read more.

Fisheries management requires the best scientific knowledge on the exploitation and conservation status of stocks. This is challenging for by-catch species, for which necessary data for their assessment is more limited than for target ones. That is the case for the thornback ray, Raja clavata, in the Balearic Islands (western Mediterranean), whose exploitation and conservation status are addressed here for the first time, in an integrative approach, by using innovative assessment methods and genetic diversity analysis. The time series of fishing landings from 1964 and MEDITS trawl survey data from 2004 were used to apply CMSY++ and Bayesian state-space Schaefer production models. We also estimated the genetic diversity of the Cytochrome C Oxidase subunit I mitochondrial gene from 31 individuals collected during MEDITS surveys. The species showed overexploitation with a current fishing mortality (F) below that producing maximum sustainable yield (F_MSY), but with a current stock biomass (B) lower than B_MSY. Despite the fact that the exploitation status is stable or even has improved in the last decades, the overexploitation period since the late 1970s seems to have reduced levels of genetic diversity, below those of related species and other populations of R. clavata. This low genetic diversity may entail the loss of adaptive potential, making the species more vulnerable to fishing and the current climate change. Full article

(This article belongs to the Special Issue Cartilaginous Fishes: Stock Assessment and Population Dynamics)

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20 pages, 11310 KiB

Open AccessArticle

Editing the Melanocortin-4 Receptor Gene in Channel Catfish Using the CRISPR-Cas9 System

by Karim Khalil, Ahmed Elaswad, Hisham Abdelrahman, Maximillian Michel, Wenbiao Chen, Shikai Liu, Ramjie Odin, Zhi Ye, David Drescher, Khoi Vo, William S. Bugg, Guyu Qin, Yujia Yang, Nathan J. C. Backenstose, Zhanjiang Liu, Roger D. Cone and Rex Dunham

Fishes 2023, 8(2), 116; https://doi.org/10.3390/fishes8020116 - 18 Feb 2023

Cited by 2 | Viewed by 2258

Abstract

The melanocortin-4 receptor (MC4R) plays a critical role in homeostasis and the regulation of body weight. Polymorphisms in the mc4r gene have been discovered and linked to growth, carcass composition, and meat quality traits. Therefore, we used the CRISPR-Cas9 system to target the [...] Read more.

The melanocortin-4 receptor (MC4R) plays a critical role in homeostasis and the regulation of body weight. Polymorphisms in the mc4r gene have been discovered and linked to growth, carcass composition, and meat quality traits. Therefore, we used the CRISPR-Cas9 system to target the mc4r gene in the most important freshwater aquaculture species in the USA, channel catfish, Ictalurus punctatus. Guide RNAs were designed to direct the Cas9 to the coding sequence of the channel catfish mc4r gene. gRNA(s)-Cas9 mixtures were delivered into one-cell embryos using electroporation and microinjection. For each treatment, the nature and rate of mutations were analyzed. Hatching and survival rates were calculated. The overall mutation rates were 30.6% and 66.7–90.6% for electroporation and microinjection, respectively. Mutated fish generated via electroporation or microinjection exhibited 38% and 20% improvement in body weight, respectively, when compared with the full-sib control. The mean feed conversion ratio of the mutants was 1.18 compared with 1.57 in the control fish. The improved growth and feed conversion indicate that the generation of mc4r-edited fish could economically benefit aquaculture production. Full article

(This article belongs to the Special Issue The Applications of Genome Editing and Genomics in Aquaculture)

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8 pages, 217 KiB

Open AccessCommunication

Norwegian Aquaculture Firms’ Emphasis on Environmental and Social Sustainability Compared to Firms in Other Industries

by Jarle Aarstad, Stig-Erik Jakobsen and Arnt Fløysand

Fishes 2023, 8(2), 115; https://doi.org/10.3390/fishes8020115 - 17 Feb 2023

Cited by 1 | Viewed by 1413

Abstract

Background: There has been a strong focus on environmental sustainability in the aquaculture industry, but we do not know how firms in this industry emphasize the issue compared to firms in other industries. Methods: Responding to this research gap, we compared survey data [...] Read more.

Background: There has been a strong focus on environmental sustainability in the aquaculture industry, but we do not know how firms in this industry emphasize the issue compared to firms in other industries. Methods: Responding to this research gap, we compared survey data of Norwegian firms in the (1) aquaculture industry with those in the (2) manufacturing industry, (3) the consulting, finance and insurance industry, and (4) the hospitality, tourism and culture industry. Results: We found that firms in the aquaculture industry emphasize environmental sustainability more than those in the other industries do. Likewise, firms in the aquaculture industry emphasize social sustainability more than those in the other industries do, but the difference is less marked. Across industries, knowledge-intensive firms emphasize environmental sustainability and social sustainability to a lesser extent. Additionally, firms with local or regional major ownership emphasize social sustainability more than those with international major ownership do. Conclusion: Firms in the aquaculture industry have a relatively strong emphasis on environmental and social sustainability, which may be due to the industry’s environmental challenges. Similarly, aquaculture firms have a relatively strong emphasis on social sustainability, which may be due to the industry’s geographic and sociocultural proximity to numerous small local communities. Full article

(This article belongs to the Section Environment and Climate Change)

12 pages, 4782 KiB

Open AccessBrief Report

Characterization of Red Sea Bream (Pagrus major) Interferon Regulatory Factor 5 and 6 Genes and Their Expression in Response to RSIV Infection

by Kyung-Ho Kim, Min-Soo Joo, Gyoungsik Kang, Won-Sik Woo, Min-Young Sohn, Ha-Jeong Son and Chan-Il Park

Fishes 2023, 8(2), 114; https://doi.org/10.3390/fishes8020114 - 16 Feb 2023

Cited by 1 | Viewed by 1529

Abstract

Interferon regulatory factors (IRFs) play crucial roles in antiviral processes, such as in the transcriptional induction of interferon (IFN) and IFN-stimulated genes (ISGs). In this study, the genes encoding IRF5 and IRF6 were identified in Pagrus major, and their expression in various [...] Read more.

Interferon regulatory factors (IRFs) play crucial roles in antiviral processes, such as in the transcriptional induction of interferon (IFN) and IFN-stimulated genes (ISGs). In this study, the genes encoding IRF5 and IRF6 were identified in Pagrus major, and their expression in various organs after pathogen infection was analyzed. In the coding sequences of P. major (Pm)IRF5 and PmIRF6, the DNA binding domain, IRF association domain, and viral-activated domain were found to be highly conserved. Phylogenetic analysis revealed that PmIRF5 and PmIRF6 were most closely related to IRF5 and IRF6 of large yellow croakers. The mRNAs for PmIRF5 and PmIRF6 were constitutively expressed in all organs analyzed but were highly expressed in the liver and gills. As a result of an infection with red sea bream iridovirus, a major pathogen of red sea bream, PmIRF5 and PmIRF6 expression was significantly upregulated in the spleen and kidney. On the basis of these results, it can be concluded that IRF5 and IRF6 expression play an influential role in the immune system of red sea bream infected with viruses. Full article

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12 pages, 540 KiB

Open AccessFeature PaperArticle

A Study on the Metabolic Rate Change Pattern in F₂ Hybrid Sturgeon, the Bester (Huso huso × Acipenser ruthenus), during the Early Developmental Stage

by Dong In Kim

Fishes 2023, 8(2), 113; https://doi.org/10.3390/fishes8020113 - 15 Feb 2023

Cited by 1 | Viewed by 1232 | Correction

Abstract

The primary goal in aquaculture is to maximize the growth and survival of farmed fishes at a minimal cost, which requires an understanding of the changes in metabolism undergone by different fish breeds during development. In particular, highly intensive aquaculture production systems, such [...] Read more.

The primary goal in aquaculture is to maximize the growth and survival of farmed fishes at a minimal cost, which requires an understanding of the changes in metabolism undergone by different fish breeds during development. In particular, highly intensive aquaculture production systems, such as recirculating aquaculture systems, require a better understanding of oxygen consumption. Ontogenetic phase shifts (i.e., sudden changes) in metabolism have been observed in several aquaculture species during early development, and such metabolic phase shifts may help to predict the oxygen consumption of aquaculture species during different stages of their development. Here, I analyzed the pattern of metabolic changes in the F₂ hybrid sturgeon, the bester (Huso huso × Acipenser ruthenus; hereafter, referred to as the F₂ bester), during its early development. I observed ontogenetic phase shifts in metabolism in the F₂ bester at body mass values of about 0.2 and 0.8 g. Thus, the F₂ bester undergoes ontogenetic phase shifts in metabolism during early development, which can help to characterize oxygen consumption at a specific developmental period. Therefore, oxygen can be appropriately adjusted and replenished during breeding. Full article

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4 pages, 203 KiB

Open AccessEditorial

Genetics and Biotechnology—The Section Editor-in-Chief’s View

by Eric M. Hallerman

Fishes 2023, 8(2), 112; https://doi.org/10.3390/fishes8020112 - 15 Feb 2023

Viewed by 913

Abstract

Genetics and biotechnology make increasingly important contributions to fishery science, fishery management, aquaculture, and related fields [...] Full article

(This article belongs to the Section Genetics and Biotechnology)

11 pages, 1290 KiB

Open AccessArticle

Fish Viscera Silage: Production, Characterization, and Digestibility of Nutrients and Energy for Tambaqui Juveniles

by Thiago Macedo Santana, Francisco de Matos Dantas, Driely Kathriny Monteiro Dos Santos, Juliana Tomomi Kojima, Yugo Moraes Pastrana, Rogério Souza De Jesus and Ligia Uribe Gonçalves

Fishes 2023, 8(2), 111; https://doi.org/10.3390/fishes8020111 - 14 Feb 2023

Cited by 3 | Viewed by 3922

Abstract

Fish viscera can be an important source of protein and energy for aquafeed, and its use contributes to circular aquaculture. The aim of this study was to produce acid and fermented silage from fish viscera to determine their nutritional value and the apparent [...] Read more.

Fish viscera can be an important source of protein and energy for aquafeed, and its use contributes to circular aquaculture. The aim of this study was to produce acid and fermented silage from fish viscera to determine their nutritional value and the apparent digestibility coefficient of nutrients and energy for juvenile tambaqui (Colossoma macropomum). An acid silage and three fermented silages with different sources of carbohydrates (molasses, wheat bran, and cassava waste) were produced with 0.25% sorbic acid as an antifungal in the formulation. Silages presented an average of 55% dry matter, 62.9% lipids, and 12% crude protein. Leucine and lysine predominated as essential amino acids in the acid silage and fermented silages. Fish viscera silages presented EPA and DHA content from 5.4 to 17.8 and 1.7 to 8.9 mg.g⁻¹ of lipids, respectively. The apparent digestibility coefficient (ADC) (indirect method) was above 82% for gross energy for all the formulations. The ADCs for protein were similar for the fermented silages, with a maximum 92% level for the fermented wheat bran silage. The bioconversion of fish viscera into silage makes it an energy ingredient for aquafeed that is well digested by tambaqui juveniles. Full article

(This article belongs to the Section Sustainable Aquaculture)

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14 pages, 1044 KiB

Open AccessArticle

Different Animal Metabolism Markers for Artemia Nauplii in Crude Protein Digestibility Assay for Lophiosilurus alexandri Larvae

by Jaqueline Simões Saliba, Fabio Aremil Costa dos Santos, Eloísa de Oliveira Simões Saliba and Ronald Kennedy Luz

Fishes 2023, 8(2), 110; https://doi.org/10.3390/fishes8020110 - 14 Feb 2023

Cited by 1 | Viewed by 1523

Abstract

This work aimed to develop a methodology for marking Artemia with different markers and evaluating their passage rate and digestibility in Lophiosilurus alexandri larvae of different ages. In the first phase, Artemia nauplii were marked 28 h after hatching with chromium oxide, titanium [...] Read more.

This work aimed to develop a methodology for marking Artemia with different markers and evaluating their passage rate and digestibility in Lophiosilurus alexandri larvae of different ages. In the first phase, Artemia nauplii were marked 28 h after hatching with chromium oxide, titanium dioxide and NANOLIPE^®. Contact times with the markers were 30, 60, 90 min at a concentration of 500 mg/L. Titanium dioxide had a higher concentration in Artemia than the other markers. The passage rate did not differ significantly between titanium and NANOLIPE^®. In the second phase, the apparent digestibility of the protein in Artemia nauplii was evaluated for L. alexandri larvae at three ages. Average real protein digestibility at the three ages was 95.08%, demonstrating Artemia as a good quality food. All ages exhibited the same final time of fecal excretion of 30 min after feeding. Artemia nauplii presented satisfactory results for assimilation for all markers tested. In determining the digestibility of Artemia protein, we can conclude that chromium oxide and NANOLIPE^® were good markers of animal metabolism and titanium dioxide was the worst marker of Artemia digestibility for the initial stages of L. alexandri. Full article

(This article belongs to the Special Issue Fish Nutrition and Physiology)

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11 pages, 1990 KiB

Open AccessArticle

High Abundance of Candidatus Arthromitus in Intestinal Microbiota of Seriolella violacea (Palm Ruff) under Reared Conditions

by Jaime Romero, Natalia Catalán, Carolina Ramírez, Claudio D. Miranda, Marcia Oliva, Héctor Flores, María Soledad Romero and Rodrigo Rojas

Fishes 2023, 8(2), 109; https://doi.org/10.3390/fishes8020109 - 13 Feb 2023

Cited by 2 | Viewed by 1549

Abstract

Intestinal microbiota has been involved in several processes that benefit the host, such as digestion, nutrient metabolism, resistance to pathogens colonization and immune function. In this study, we investigated the diversity, composition and functional prediction of microbiota of reared Seriolella violacea (palm ruff) [...] Read more.

Intestinal microbiota has been involved in several processes that benefit the host, such as digestion, nutrient metabolism, resistance to pathogens colonization and immune function. In this study, we investigated the diversity, composition and functional prediction of microbiota of reared Seriolella violacea (palm ruff) in the same cohort sampled at different times (7-, 8- and 9-month-old). Microbial community structure analyses, using 16S rRNA amplicon sequencing, revealed that the intestinal microbiota was dominated by the phyla Firmicutes, Proteobacteria, Fusobacteria and Tenericutes. At the genus level, Candidatus Arthromitus was the most abundant in all sampled timepoints, representing in average 78% of the bacterial community (ranging from 18 to 98%), corresponding to segmented filamentous bacteria, which are interesting because they have been associated with the maturation of immune responses in the gut and protecting the host from bacterial infections. The comparisons of the intestinal microbiota among the three groups showed differences in abundance of bacterial taxa and also in alpha diversity indexes (Shannon and Simpson), as well as beta diversity metrics (weighted and unweighted UniFrac). Potential functions of the intestinal microbiota of palm ruff were retrieved using Philipin and Tax4fun and these analyses revealed high levels of genes for sugar metabolism. To our knowledge, this study represents the first description of the intestinal microbiota of S. violacea. Full article

(This article belongs to the Special Issue Gut Microbiota in Fish and Shellfish)

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14 pages, 11191 KiB

Open AccessArticle

Effects of Multiple Freeze-Thaw Cycles on Protein and Lipid Oxidation, Microstructure and Quality Characteristics of Rainbow Trout (Oncorhynchus mykiss)

by Ningning Du, Yanchun Sun, Zhongxiang Chen, Xiaoli Huang, Chenhui Li, Lei Gao, Shuyan Bai, Peng Wang and Qirui Hao

Fishes 2023, 8(2), 108; https://doi.org/10.3390/fishes8020108 - 13 Feb 2023

Cited by 7 | Viewed by 2122

Abstract

Multiple freeze-thaw cycles due to temperature fluctuations irreversibly damage the muscle tissue of fish, thereby reducing their edibility. The aim of this study was to determine the effects of the number of freeze-thaw (F–T) cycles on protein and lipid oxidation, microstructure, physical index, [...] Read more.

Multiple freeze-thaw cycles due to temperature fluctuations irreversibly damage the muscle tissue of fish, thereby reducing their edibility. The aim of this study was to determine the effects of the number of freeze-thaw (F–T) cycles on protein and lipid oxidation, microstructure, physical index, and nutritional quality of rainbow trout muscle. The results showed that F–T cycles accelerated protein carbonyl formation and thiobarbituric acid reactive substances (TBARS) generation (p < 0.05), as well as increased the loss of total sulfhydryl (SH) groups (p < 0.05). Moreover, transmission electron microscope (TEM) images illustrated that the microstructure of muscle fibers was loosed and disintegrated after the third F–T cycle, causing a reduction in water holding capacity (WHC). In addition, muscles lost the intrinsic color of fresh meat after the fifth cycle, with lightness L* and yellowness b* increasing, while redness a* declined (p < 0.05). The hardness, springiness, and chewiness of muscles decreased, and the shear force first increased and then decreased after the third cycle. Furthermore, the proximate components, essential amino acids (EAAs), and total amino acids (TAAs), decreased significantly after the third cycle (p < 0.05) due to the decrease of WHC as well as protein and lipid oxidation. The results indicated that the quality of rainbow trout muscle changed after the third cycle, deteriorated seriously after the fifth cycle, and was unacceptable after the seventh cycle. Therefore, it is necessary to reduce the temperature fluctuation to less than three times during freezing. The results provided a reference for the identification and classification of frozen aquatic products. Full article

(This article belongs to the Section Physiology and Biochemistry)

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21 pages, 5144 KiB

Open AccessArticle

Genome-Wide Identification, Phylogenetic Analysis and Expression Pattern Profiling of the Aquaporin Family Genes in Leuciscus waleckii

by Feifei Zhan, Liqun Liang, Shuangyi Wang, Honjung Liew, Yumei Chang and Limin Zhang

Fishes 2023, 8(2), 107; https://doi.org/10.3390/fishes8020107 - 11 Feb 2023

Cited by 1 | Viewed by 1564

Abstract

Aquaporin (Aqp) is a transmembrane-specific channel for small molecules that help in regulating homeostasis in fishes when adapting to changing environments, but its role in Amur ide’s response to alkaline stress is yet to be revealed. Therefore, the purpose of this study is [...] Read more.

Aquaporin (Aqp) is a transmembrane-specific channel for small molecules that help in regulating homeostasis in fishes when adapting to changing environments, but its role in Amur ide’s response to alkaline stress is yet to be revealed. Therefore, the purpose of this study is to investigate the response of the Aqp gene exposed to alkaline water in Amur ide (Leuciscus waleckii) using a genome-transcriptional assay. Based on the results, we classified the Aqps of the L. waleckii (LwAqps) genome and analyzed its transcriptional expression profile and genetic evolution under carbonate alkalinity stress. A total of 18 Aqp genes were identified in four grades in L. waleckii. The highest Aqp gene expression was found in the gill and kidney of L. waleckii from the Wusuli River (WSL) in comparison to those in the Dali Lake (DL), whereas aqp3a, -3ap1, -7, and -9a expressions were found at intensively higher levels in the gill rather than in the kidneys and livers. The experiment of L. waleckii under alkalinity stress (carbonate alkalinity 50 mmol·L⁻¹) and its recovery showed that the expressions of aqp0a, -3a, -3ap1, -7, -8aa, and -9a were upregulated in alkaline water and downregulated in freshwater. We identified 1460 single nucleotide polymorphism (SNP) markers in the Aqp genes. The average value of Fst of SNP markers in the CDS region was 0.177 ± 0.256, and the first 5% SNPs were identified at aqp3a and -11b. Residue Ser66 does not bring about an overall change in the three-dimensional structure of Aqp3a, but may change the penetration of solutes across the membrane. This indicates that Aqp genes are involved in the response of L. waleckii to alkaline stress, and aqp3a is one of the key genes involved in regulating L. waleckii’s adaptation to alkaline environments. Full article

(This article belongs to the Special Issue The Applications of Genome Editing and Genomics in Aquaculture)

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14 pages, 3473 KiB

Open AccessArticle

Reproductive Characteristics of Pseudecheneis sulcatus (Siluriforms: Sisoridae) in the Lower Yarlung Zangbo River, Tibet

by Pengcheng Lin, Huaming Hu, Zheng Gong, Jian Wang and Xin Gao

Fishes 2023, 8(2), 106; https://doi.org/10.3390/fishes8020106 - 10 Feb 2023

Cited by 1 | Viewed by 2010

Abstract

The present research offers novel understandings of the reproductive biology of Pseudecheneis sulcatus (McClelland, 1842) found in the Yarlung Zangbo Grand Canyon, a biodiversity hotspot. Reproductive characteristics of Pseudecheneis sulcatus, including their maturation age, fertility, spawning season, and maximum body size, constitute [...] Read more.

The present research offers novel understandings of the reproductive biology of Pseudecheneis sulcatus (McClelland, 1842) found in the Yarlung Zangbo Grand Canyon, a biodiversity hotspot. Reproductive characteristics of Pseudecheneis sulcatus, including their maturation age, fertility, spawning season, and maximum body size, constitute important aspects of its life-history traits. We collected a total of 310 specimens from the Yarlung Zangbo River’s Motuo reach between March and November 2016 and found the male-to-female ratio to be 0.73:1, markedly different from the anticipated 1:1. The total length of individuals ranged from 72 to 207 mm, while overall weight ranged from 2.5 to 65.0 g. Their length at first maturity was estimated as 131 mm in males and 132 mm in females. Based on the adult proportion and fluctuation in the monthly gonadosomatic index (GSI) and size distribution of oocytes, spawning was determined to occur from March to June. The absolute fecundity ranged between 247 and 2886 eggs, while the fluctuation in average relative fertility ranged between 16.8 and 77.1 eggs/g of fish. The fecundity of P. sulcatus was linearly correlated to the overall weight and length of the fish along with the ovarian weight. In conclusion, P. sulcatus spawned synchronously in spring and early summer, exhibiting low fecundity and large oocytes. Our results provided basic information in understanding how this species adapted well to the unique canyon environment, which may be useful for developing a sustainable conservation plan for P. sulcatus at the lower reach of the Yarlung Zangbo River. Full article

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15 pages, 1536 KiB

Open AccessArticle

Potential Symbiotic Effects of β-1,3 Glucan, and Fructooligosaccharides on the Growth Performance, Immune Response, Redox Status, and Resistance of Pacific White Shrimp, Litopenaeus vannamei to Fusarium solani Infection

by El-Sayed Hemdan Eissa, Ragaa A. Ahmed, Nadia A. Abd Elghany, Amal Elfeky, Saadea Saadony, Norhan H. Ahmed, Salah El-Sayed Sakr, Geraldine B. Dayrit, Charlene Princess S. Tolenada, Adlene Anne C. Atienza, Mahmoud Mabrok and Hala F. Ayoub

Fishes 2023, 8(2), 105; https://doi.org/10.3390/fishes8020105 - 10 Feb 2023

Cited by 14 | Viewed by 3114

Abstract

The potential effects of dietary supplementation with β-1,3 glucan and fructooligosaccharides (β-1,3 GF) on antioxidant activities, immunological response, and growth performance of Pacific white shrimp (Litopenaeus vannamei) was investigated. Four diets (iso-energetic and iso-nitrogenous) with different levels of β-1,3 GF (0, [...] Read more.

The potential effects of dietary supplementation with β-1,3 glucan and fructooligosaccharides (β-1,3 GF) on antioxidant activities, immunological response, and growth performance of Pacific white shrimp (Litopenaeus vannamei) was investigated. Four diets (iso-energetic and iso-nitrogenous) with different levels of β-1,3 GF (0, 0.5, 1.0, and 1.5 g kg⁻¹) were fed to healthy shrimp juveniles weighing 3 ± 0.5 g for 75 days. Shrimps were randomly distributed into 12 net enclosures at a density of 30 shrimp/net, and the experiment was performed in triplicate. The results revealed that long-term supplementation with 1.5 g kg⁻¹ β-1,3 GF significantly improved shrimp weight gain, feed conversion ratio, and digestive enzyme profiles compared to the control diet group. However, there were no substantial variations in the contents of moisture, crude protein, total lipids, and ash in the muscles of shrimp fed on different diets. Surprisingly, all antioxidants (superoxide dismutase, catalase, glutathione peroxidase) and immune biomarkers (lysozyme, total hemocyte count, phenol oxidase, and respiratory burst) activities were significantly elevated with increasing levels of β-1,3 GF in the shrimp diet, and the highest values were recorded in the 1.5 g kg⁻¹ diet groups. Challenge test results revealed that F. solani could cause a high mortality rate (86.7%) in a group fed a normal basal diet within 14 days at a dose of 5 × 10⁴ conidia mL⁻¹. Surprisingly, all dietary treated groups with different doses of β-1,3 GF showed high resistance against F. solani, represented by lower cumulative mortality rates (20–43.3%) compared to the control group. Moreover, most of the infected shrimp showed a typical black to brown gill lesion similar to that observed in the natural infection, where an identical fungus was successfully re-isolated from infected gills and muscles. Overall, this study recommends an appropriate incorporation level of β-1,3 GF that could enhance growth performance and improve the antioxidant activities, non-specific immunity, and disease resistance of L. vannamei, with an optimal level of 1.5 g kg⁻¹. Full article

(This article belongs to the Special Issue Disease Control in Fish and Shrimp Aquaculture)

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18 pages, 9458 KiB

Open AccessFeature PaperArticle

Fostering the Development of Western Black Sea Aquaculture: A Scientific Case Study for Finfish Cage Farming Allocated Zone Designation

by Magda Nenciu, Victor Niță, Luminița Lazăr, Alina Spînu and Elena Vlăsceanu-Mateescu

Fishes 2023, 8(2), 104; https://doi.org/10.3390/fishes8020104 - 09 Feb 2023

Cited by 2 | Viewed by 1562

Abstract

Mariculture offers enormous potential for providing sustainable food, playing a key role in achieving nutrition security, employment, and Blue Growth. This is particularly true in geographical areas where the dependence of local economies on fishery products is high and yet access to sustainable [...] Read more.

Mariculture offers enormous potential for providing sustainable food, playing a key role in achieving nutrition security, employment, and Blue Growth. This is particularly true in geographical areas where the dependence of local economies on fishery products is high and yet access to sustainable landings is hindered by environmental drawbacks. One such area is represented by the Black Sea, which offers different degrees of suitability for aquaculture development. While the southern and eastern shores are sheltered enough to allow for the development of large aquaculture activities, the north-western shoreline is characterized by wide environmental fluctuations and the strong influence of the Danube. This study aimed at investigating the suitability of a selected area of the Romanian coast (Mangalia) for finfish cage farming by adapting an internationally endorsed methodology for determining its Degree of Compatibility (DC). The development and expansion of finfish aquaculture depends on the availability of space, so designating Allocated Zones for Aquaculture (AZAs) is essential. The result obtained (DC = 80) indicates that the Mangalia area is suitable for finfish aquaculture activities: there is no major interference with other uses of the maritime space, no conflicts with nature conservation, and the environmental conditions are appropriate for fish culture in floating cages. The novel information provided by this study can be the building block for authorities to settle the governance gap that has so far impeded the development of marine aquaculture in Romania. At a larger scale, this study can serve as a good practice example at the regional Black Sea level. Full article

(This article belongs to the Special Issue Aquaculture Economics and Fisheries Management)

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8 pages, 396 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

17β-Estradiol Can Induce Sex Reversal in Brown Trout

by Jill M. Voorhees, Elizabeth R. J. M. Mamer, Daniel J. Schill, Mitchel Adams, Carlos Martinez and Michael E. Barnes

Fishes 2023, 8(2), 103; https://doi.org/10.3390/fishes8020103 - 09 Feb 2023

Cited by 3 | Viewed by 2174

Abstract

Hormones have been used to change phenotypic sex in many fish species. However, information specific to changing sex in brown trout Salmo trutta is lacking. This study compared the effectiveness of two different 17β-estradiol (estradiol) concentrations (20 mg/kg and 30 mg/kg) fed to [...] Read more.

Hormones have been used to change phenotypic sex in many fish species. However, information specific to changing sex in brown trout Salmo trutta is lacking. This study compared the effectiveness of two different 17β-estradiol (estradiol) concentrations (20 mg/kg and 30 mg/kg) fed to brown trout for 60 days, beginning at initial feeding. At 456 days post-initial feeding, the 20 mg/kg and 30 mg/kg treatment groups were 84% and 86% female, respectively. These values were significantly higher than the 47% females observed in the control group which did not receive dietary estradiol. At the end of the 60-day estradiol treatment period, weight gain, percent weight gain, and feed conversion ratio were all significantly lower in the tanks of fish receiving estradiol than in the control tanks. Individual fish fed estradiol also weighed significantly less and were significantly shorter than the fish not receiving estradiol-coated feed. Mortality ranged from 1.0 to 2.4% among the treatments and was not significantly different. After 105 days post-initial feeding, weight gain, percent weight gain, and feed conversion ratio were not significantly different among the treatments. At 456 days post-initial feeding, individual fish were significantly longer and heavier in the 20 mg/kg estradiol treatment compared to the fish in the control treatment, and the fish in the 30 mg/kg estradiol treatment were similar to the other two treatments. This study is the first to document the successful sex reversal of brown trout using estradiol. While the estradiol treatments used in this study did not lead to complete feminization, the observed 85-to-15% female-to-male phenotypic ratio indicates the successful feminization of genetic males. The levels of feminization observed in this study are suitable for this initial step to potentially develop a YY male broodstock to control invasive brown trout populations. Full article

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34 pages, 7272 KiB

Open AccessReview

Shellfish as Biosensors in Online Monitoring of Aquatic Ecosystems: A Review of Russian Studies

by Alexander G. Dvoretsky and Vladimir G. Dvoretsky

Fishes 2023, 8(2), 102; https://doi.org/10.3390/fishes8020102 - 08 Feb 2023

Cited by 7 | Viewed by 5776

Abstract

The use of biological objects in monitoring the state of the environment and the changes caused by the impact of environmental pollution on marine and fresh waters is a promising tool due to a lower cost in comparison to traditional monitoring and the [...] Read more.

The use of biological objects in monitoring the state of the environment and the changes caused by the impact of environmental pollution on marine and fresh waters is a promising tool due to a lower cost in comparison to traditional monitoring and the ability to receive immediate information about the ecosystem status. In this review, we summarize the biological information about shellfish biomonitors and the results of studies focused on the development and use of the bioindicator species in early warning systems in Russia. Since the mid-1980s, Russian specialists have developed online biomonitoring systems; as in the rest of world, there are two main approaches that are currently applied to study the physiological status of potential biosensor shellfish species and to monitor freshwater and marine systems: valvometry (registration of gaping activity in bivalve mollusks) and photoplethysmography (registration of cardiac activity in mollusks and crustaceans). Valve movement responses to stressors such as abnormal conditions and pollutants include the closure of shell valves for a long period, decrease in the average distance between valves, rapid shell opening, and higher closing frequency. Cardiac activity reactions of shellfish to stress factors include rapid increases in heart rate and stress index, higher variability in heart rate than under normal conditions, and longer periods required for heart rate recovery after stress. The most common bioindicators used to monitor environmental disturbances in marine ecosystems are blue mussels, Iceland scallops, and red king crabs in cold-water habitats and Black Sea mussels in warmer waters as well as freshwater mussels and crayfish in fresh waters. Full article

(This article belongs to the Special Issue Response of Aquatic Animals to Environmental Changes)

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10 pages, 853 KiB

Open AccessBrief Report

Filter-Feeding Pacific Lamprey (Entosphenus tridentatus) Ammocetes Can Reduce Suspended Concentrations of E. coli Bacteria

by Parker Kalan, John Steinbeck, Freddy Otte, Sean C. Lema and Crow White

Fishes 2023, 8(2), 101; https://doi.org/10.3390/fishes8020101 - 08 Feb 2023

Cited by 1 | Viewed by 1669

Abstract

Filter-feeding invertebrates such as bivalves have been shown to improve the health of aquatic systems by reducing concentrations of bacteria and other harmful suspended organisms, but it remains unknown if microphagous suspension-feeding fishes can provide similar ecosystem services for water quality. Here, we [...] Read more.

Filter-feeding invertebrates such as bivalves have been shown to improve the health of aquatic systems by reducing concentrations of bacteria and other harmful suspended organisms, but it remains unknown if microphagous suspension-feeding fishes can provide similar ecosystem services for water quality. Here, we tested whether the presence of the filter-feeding larval ammocoete life-stage of Pacific lamprey (Entosphenus tridentatus) can reduce suspended concentrations of Escherichia coli bacteria. Aquaria containing either filter-feeding ammocoete lamprey larvae (1.5 fish·L⁻¹), lamprey macropthalmia juveniles (1.5 fish·L⁻¹) that do not suspension-feed, or no lamprey (control) were filled with water contaminated with E. coli bacteria and then monitored for 5 d for E. coli concentration changes in the water column. The presence of ammocoete larvae generated a significantly faster decline in E. coli abundance compared to aquaria containing either macropthalmia-stage lamprey or no fish, which showed similar E. coli concentration profiles over that 5 d period. A higher density of ammocoetes (4.3 fish·L⁻¹) resulted in a more rapid decline in E. coli compared to the lower 1.5 fish·L⁻¹ ammocoete density, further implying that ammocoetes augmented bacterial clearance. These observations provide evidence that filter-feeding larval ammocoetes of Pacific lamprey may help promote water-quality enhancement by reducing suspended bacterial concentrations. Full article

(This article belongs to the Section Nutrition and Feeding)

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12 pages, 2114 KiB

Open AccessFeature PaperArticle

Effects of Climate Variability on Two Commercial Tuna Species Abundance in the Indian Ocean

by Yang Wang, Fan Zhang, Zhe Geng, Yuying Zhang, Jiangfeng Zhu and Xiaojie Dai

Fishes 2023, 8(2), 99; https://doi.org/10.3390/fishes8020099 - 07 Feb 2023

Cited by 6 | Viewed by 2326

Abstract

Oceanic temperature fluctuations are one of the leading factors affecting marine fish populations. Indian Ocean Dipole (IOD), characterized as the sea surface temperature (SST) anomaly change, is an ocean–atmosphere interactive process causing interannual climate variability in the Indian Ocean. Influences of the IOD [...] Read more.

Oceanic temperature fluctuations are one of the leading factors affecting marine fish populations. Indian Ocean Dipole (IOD), characterized as the sea surface temperature (SST) anomaly change, is an ocean–atmosphere interactive process causing interannual climate variability in the Indian Ocean. Influences of the IOD on the tuna catch rates are supported by previous research. Yet, there remains limited information about the impacts on the abundance of tuna stocks. In this study, we used the standardized Catch Per Unit Effort (CPUE) index to present the stock abundance and compared the effects of the IOD on the bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares) among different management areas of the Indian Ocean Tuna Commission (IOTC). Results show significant correlations between IOD events on both species’ abundance in the tropical western Indian Ocean. However, in the tropical eastern Indian Ocean and the southern Indian Ocean, neither bigeye nor yellowfin tuna abundances were significantly correlated by the IOD. For the whole Indian Ocean, IOD was significantly correlated uniquely with the yellowfin tuna abundance. Our results emphasized the importance of evaluating the climate variability effects over fisheries abundance species by species and per fishing areas analyses. Full article

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18 pages, 8410 KiB

Open AccessArticle

The Responses of Sediment Bacterial Communities in Chinese Mitten Crab (Eriocheir sinensis) Culture Ponds to Changes in Physicochemical Properties Caused by Sediment Improvement

by Tianheng Gao, Nannan Li, Wenlei Xue, Yuning Hu and Hai Lin

Fishes 2023, 8(2), 98; https://doi.org/10.3390/fishes8020098 - 07 Feb 2023

Cited by 1 | Viewed by 1863

Abstract

The interaction between nutrients, heavy metals, and sediment bacterial communities play a key role in the health of crabs and the biogeochemical cycles of aquaculture systems. However, the effects of sediment improvement activities in crab culture on nutrients and heavy metals and the [...] Read more.

The interaction between nutrients, heavy metals, and sediment bacterial communities play a key role in the health of crabs and the biogeochemical cycles of aquaculture systems. However, the effects of sediment improvement activities in crab culture on nutrients and heavy metals and the response of bacterial communities to the relevant changes are unclear. In this study, 24 water and sediment samples were collected from two aquaculture sites (total of 12 ponds, 6 at each site). High-throughput sequencing was used to determine the structure of the bacterial community and the diversity in water and sediment samples. The relationship between nutrients, heavy metals, and bacterial communities and the changes of the three before and after the improvement of the sediment were analyzed. The results showed that Proteobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, and Firmicutes were predominant at the phylum level of sediment. Sediment improvement has an effect on NH₄⁺-N, sulfide, total organic carbon (TOC), and heavy metals in sediments to varying degrees. In addition, redundancy analysis found that NH₄⁺-N, NO₃⁻-N, TP, and heavy metals were key drivers in crab culture pond sediments. The results of functional prediction showed that carbon, nitrogen, and sulfur metabolism were the dominant processes in the two crab farming areas. Overall, changes in nutrients and heavy metals caused by sediment improvement further affected the structure and function of bacterial communities and may affect biogeochemical cycles. Our study has deepened the understanding of the effects of sediment improvement on nutrients, heavy metals, and bacterial communities in crab culture ponds. Full article

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19 pages, 2975 KiB

Open AccessArticle

Bluegill Population Demographics as Related to Abiotic and Biotic Factors in Florida Lakes

by Andrew K. Carlson and Mark V. Hoyer

Fishes 2023, 8(2), 100; https://doi.org/10.3390/fishes8020100 - 07 Feb 2023

Cited by 1 | Viewed by 1876

Abstract

Research on Bluegills, Lepomis macrochirus R., is abundant but typically focuses on water bodies with similar environmental conditions. We assessed Bluegill density, relative abundance (catch per unit effort [CPUE] by electrofishing), growth, and size structure in 60 lakes with wide-ranging surface areas (2–12,412 [...] Read more.

Research on Bluegills, Lepomis macrochirus R., is abundant but typically focuses on water bodies with similar environmental conditions. We assessed Bluegill density, relative abundance (catch per unit effort [CPUE] by electrofishing), growth, and size structure in 60 lakes with wide-ranging surface areas (2–12,412 ha), trophic states (oligotrophic–hypereutrophic), and macrophyte abundances (0.3–100 percent of lake volume inhabited [PVI]) across Florida, USA. Bluegill density and CPUE increased with lake productivity and decreased with macrophyte abundance. Bluegill growth increased with lake productivity and CPUE of stock-length Florida Bass, Micropterus floridanus L., a Bluegill predator. Bluegill size structure increased with lake productivity and decreased with Bluegill density. Results indicate that Bluegill fisheries with abundant individuals of quality size (≥150 mm) require productive (>25 μg/L chlorophyll-a concentration) lakes with moderate to high macrophyte coverage (PVI 50–100), abundant stock-length Florida Bass (>40 fish/h of electrofishing), and Bluegill densities <300 fish/ha. This study provides an approach to predict Bluegill population demographics based on abiotic and biotic factors, establish fisheries management expectations, and develop regional and lake-specific management tools. Full article

(This article belongs to the Section Biology and Ecology)

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3 pages, 216 KiB

Open AccessEditorial

Aquatic Pollutants: Risks, Consequences, Possible Solutions and Novel Testing Approaches

by Maria Dulce Estêvão

Fishes 2023, 8(2), 97; https://doi.org/10.3390/fishes8020097 - 06 Feb 2023

Cited by 1 | Viewed by 976

Abstract

It is undeniable that there is a wide variety of pollutants in the various water bodies around the planet, including organic and inorganic compounds, pathogenic microorganisms, and microplastics [...] Full article

(This article belongs to the Special Issue Aquatic Pollutants: Risks, Consequences, Possible Solutions and Novel Testing Approaches)

25 pages, 2736 KiB

Open AccessCase Report

Bioeconomic Analysis of In-Pond Raceway System Production of Foodsize and Stocker Hybrid Catfish (Channel Catfish Ictalurus punctatus ♀ × Blue Catfish, I. furcatus ♂)

by Leticia Fantini-Hoag, Terry Hanson and Jesse Chappell

Fishes 2023, 8(2), 96; https://doi.org/10.3390/fishes8020096 - 06 Feb 2023

Viewed by 1622

Abstract

The U.S. catfish industry is seeking production systems that are efficient, intensive, and profitable. Growing foodsize and stocker-sized fish in the same pond is attractive as it is often difficult to obtain larger-sized stockers early each year. This case study evaluated the performance [...] Read more.

The U.S. catfish industry is seeking production systems that are efficient, intensive, and profitable. Growing foodsize and stocker-sized fish in the same pond is attractive as it is often difficult to obtain larger-sized stockers early each year. This case study evaluated the performance and economics of producing foodsize hybrid catfish and stocker-sized fingerlings in in-pond raceway systems (IPRS) placed into four 0.4 ha ponds. Growout raceways (RW1/RW2) in ponds 1 and 2 were 63 m³, and 45 m³ in ponds 3 and 4 (RW3/RW4). Each pond had one (14 m³) stocker unit raceway and a 5 HP of aeration that maintained adequate dissolved oxygen levels. Average growout production was 12,050 kg/ha in 63 m³ raceways and 12,078 kg/ha in 45 m³ raceways (228 days of production) and achieved harvest weights ranging from 564 to 661 g. The raceway stocker unit had production yields ranging from 3537 to 4388 kg/ha (143 days of production) and achieved harvest weights ranging from 123 to 234 g. Stocker units in ponds 1 and 2 generated 8540 stocker–fingerlings (21,102 fingerlings/ha) and units in ponds 3 and 4 generated 7954 fingerlings (19,654 fingerlings/ha). An investment of USD 39,996 was needed for ponds 1 and 2 and USD 21,196 for ponds 3 and 4. When scenarios were analyzed financially, positive financial net returns occurred when farm level investment decreased, leading to reduced payback periods, increased net present values, and higher internal rates of return. IPRS used stocker units to culture fingerlings for future stocking of foodsize fish. IPRS provided good inventory control, and high production yields compared to traditional pond culture of catfish. Full article

(This article belongs to the Special Issue Advances in Understanding of Fish and Aquatic Animals: Reviews of Current Topics)

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14 pages, 4829 KiB

Open AccessArticle

Otolith Morphometric and Shape Distinction of Three Redfin Species under the Genus Decapterus (Teleostei: Carangidae) from Sulu Sea, Philippines

by Christian James C. Morales, Kyle Dominic E. Barnuevo, Emmanuel S. Delloro, Jr., Roxanne A. Cabebe-Barnuevo, Jenylle Kate S. Calizo, Sanny David P. Lumayno and Ricardo P. Babaran

Fishes 2023, 8(2), 95; https://doi.org/10.3390/fishes8020095 - 05 Feb 2023

Cited by 4 | Viewed by 3720

Abstract

Otoliths are paired calcified structures in the inner ear of teleosts that function in hearing and balance. In this study, the use of otolith morphometrics and shape analysis were explored to delineate the redfin species under the genus Decapterus from the Sulu Sea, [...] Read more.

Otoliths are paired calcified structures in the inner ear of teleosts that function in hearing and balance. In this study, the use of otolith morphometrics and shape analysis were explored to delineate the redfin species under the genus Decapterus from the Sulu Sea, Philippines, namely, Decapterus kurroides, D. smithvanizi, and D. tabl. Results showed that the mean otolith shapes are unique within species (p < 0.001). The otolith size-related (OW—otolith weight, OL—otolith length, OH—otolith height, OA—otolith area, and OP—otolith perimeter) and shape-related (RE—rectangularity, SQ—squareness, EL—ellipticity, RO—roundness, AR—aspect ratio, FF—form factor, CO—compactness, and CI—circularity) morphometric indices also showed significant variations (p < 0.001) among the three species. Distinct regions differentiating D. kurroides from the other two species were seen along the dorsal margin of the otoliths, which was supported by its significantly higher values for OH (size-related index) and RO (shape-related index). In addition, the morphometric indices showed significant variations (p < 0.001), except for RE. Furthermore, it was revealed that the size-related indices were able to separate D. kurroides from the other two species, which turned out to be indifferent. The results provided relevant data on the use of otoliths as an additional confirmatory tool in species delineation of the identified redfin species, and, therefore, offer opportunities of applying the same method in delineation and, eventually, identification of species from other genera, especially those that closely resemble each other. Full article

(This article belongs to the Special Issue Otoliths and Their Applications in Fishery Science II)

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17 pages, 3102 KiB

Open AccessArticle

Transcriptomic Analysis and Functional Gene Expression in Different Stages of Gonadal Development of Macrobrachium rosenbergii

by Zhenxiao Zhong, Guozhu Chen, Haihui Tu, Xinyi Yao, Xin Peng, Xuan Lan, Qiongying Tang, Shaokui Yi, Zhenglong Xia, Miaoying Cai and Guoliang Yang

Fishes 2023, 8(2), 94; https://doi.org/10.3390/fishes8020094 - 05 Feb 2023

Cited by 3 | Viewed by 1658

Abstract

In order to decipher the functional genes and reveal the molecular mechanism of gonadal development in Macrobrachium rosenbergii, a comparative transcriptome analysis was performed on the testes and ovaries at different developmental stages. A total of 146,537 unigenes with an N50 of [...] Read more.

In order to decipher the functional genes and reveal the molecular mechanism of gonadal development in Macrobrachium rosenbergii, a comparative transcriptome analysis was performed on the testes and ovaries at different developmental stages. A total of 146,537 unigenes with an N50 of 2008 bp and an average length of 1144 bp were obtained from the sequencing raw data via quality control and denovo assembly. Identification of differentially expressed genes (DEGs) showed that there were 339 and 468 DEGs among the different developmental stages of testes and ovaries, respectively, and 7993 DEGs between the testes and ovaries. The KEGG enrichment analysis identified 13 candidate pathways related to gonadal development, including insulin synthesis, oocyte maturation, and steroid biosynthesis, which were involved in biological processes such as regulation of hormone metabolism, sex cell proliferation and development, and amino acid metabolism. The DEGs related to the above pathways such as insulin-like growth factor 1 receptor (IGF1R), heat shock protein 90 (Hsp 90), and cyclooxygenase (COX) genes were highly expressed during yolk protein synthesis, indicating that these genes might be involved in yolk accumulation and oogenesis. Meanwhile, calmodulin (CaM) and other genes were highly expressed during spermatogenesis, suggesting that these genes might play an important role in spermatogenesis. Ten differentially expressed genes in the KEGG signaling pathway, including CRQ, COX, APP, Cdc42, Hsd17b12, Art-1, Hsp70, Hsp90, PRMT1, and GP, were selected for real-time quantitative PCR (RT- qPCR) to validate the transcriptome data, and the results showed that RT- qPCR obtained consistent results with the RNA-Seq data. The present findings provide new insights into the molecular regulation mechanism of gonadal development in M. rosenbergii. Full article

(This article belongs to the Special Issue Transcriptomics in Aquaculture: Current Status and Applications)

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24 pages, 757 KiB

Open AccessReview

Main Components of Fish Immunity: An Overview of the Fish Immune System

by Doaa M. Mokhtar, Giacomo Zaccone, Alessio Alesci, Michal Kuciel, Manal T. Hussein and Ramy K. A. Sayed

Fishes 2023, 8(2), 93; https://doi.org/10.3390/fishes8020093 - 05 Feb 2023

Cited by 41 | Viewed by 12174

Abstract

Cellular immune responses consist of innate and adaptive cell-mediated immune mechanisms, where all leukocyte subpopulations are included. Among these are vital processes such as cell-mediated cytotoxicity and phagocytosis. The main cellular constituents of the fish immune system are macrophages, granulocytes, dendritic cells, NK [...] Read more.

Cellular immune responses consist of innate and adaptive cell-mediated immune mechanisms, where all leukocyte subpopulations are included. Among these are vital processes such as cell-mediated cytotoxicity and phagocytosis. The main cellular constituents of the fish immune system are macrophages, granulocytes, dendritic cells, NK cells, and cytotoxic T cells. This review provides the latest information on cellular defense mechanisms of fish and provides an overview of the function of the mucosal immune system in maintaining the general health of fish. Here, we discuss the fundamental ideas that underpin mucosal immune responses in teleosts, as well as the innate and adaptive immune cells and the molecules that play a role in these immune responses. Moreover, cytokine molecules and pathways in teleosts have been reported to focus on several kinds of associated immunity. Importantly, we also review antigen processing and presentation. The knowledge reported here will enable better understanding, determination, and modulation of the pathways responsible for protective immunity, thus consequently improving the health of the fish in aquaculture. Full article

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13 pages, 2593 KiB

Open AccessArticle

Transcriptomic and Metabolomic Analyses of Palaemon carinicauda Hepatopancreas in Response to Enterocytozoon hepatopenaei (EHP) Infection

by Guangwei Hu, Weili Wang, Kai Xu, Chao Wang, Dexue Liu, Jing Xu, Binlun Yan, Nanjing Ji and Huan Gao

Fishes 2023, 8(2), 92; https://doi.org/10.3390/fishes8020092 - 05 Feb 2023

Cited by 7 | Viewed by 1870

Abstract

Enterocytozoon hepatopenaei (EHP), a microsporidian responsible for hepatopancreatic microsporidiosis, is a major pathogen in commercial shrimp production. Among the affected species, Palaemon carinicauda (formerly Exopalaemon carinicauda) is commercially important in China and represents a potential research model for studying crustaceans. However, little [...] Read more.

Enterocytozoon hepatopenaei (EHP), a microsporidian responsible for hepatopancreatic microsporidiosis, is a major pathogen in commercial shrimp production. Among the affected species, Palaemon carinicauda (formerly Exopalaemon carinicauda) is commercially important in China and represents a potential research model for studying crustaceans. However, little information is available on its response to EHP infection. Hence, this study analyzed the transcriptome and metabolome of P. carinicauda’s hepatopancreas using high-throughput sequencing and liquid chromatograph-mass spectrometry (LC-MS) to determine its response during the early stage of infection. The transcriptomic analyses identified 730 differentially expressed genes, of which those associated with EHP infection were enriched in metabolic pathways as well as detoxification and antioxidant pathways. In addition, 144 differential metabolites were identified using a combination of positive and negative ion modes in LC-MS. The Kyoto encyclopedia of genes and genomes pathway analyses further indicated that the degradation of aromatic compounds, the AMP-activated protein kinase signaling pathway and C5-branched dibasic acid metabolism were significantly enriched after EHP infection. These results could provide useful insights into the effects of EHP on shrimps during the early stages of infection and help to understand the mechanisms underlying the stunted growth of shrimps after infection. Full article

(This article belongs to the Special Issue Transcriptomics in Aquaculture: Current Status and Applications)

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8 pages, 1291 KiB

Open AccessCommunication

Fish Biozonation in the Balkan Peninsula, Especially in Bulgaria: A Challenge

by Apostolos Apostolou, Luchezar Pehlivanov, Michael Schabuss, Horst Zornig and Georg Wolfram

Fishes 2023, 8(2), 91; https://doi.org/10.3390/fishes8020091 - 03 Feb 2023

Cited by 1 | Viewed by 1018

Abstract

Fish are important elements of aquatic ecosystems. Their communities naturally follow the river continuum and have been well described in the western European freshwater watersheds. In regions of higher endemism, such as the Balkan Peninsula, the widely accepted fish zonation of Illies is [...] Read more.

Fish are important elements of aquatic ecosystems. Their communities naturally follow the river continuum and have been well described in the western European freshwater watersheds. In regions of higher endemism, such as the Balkan Peninsula, the widely accepted fish zonation of Illies is doubtfully relevant. In this study, a more suitable categorization of lotic and lentic freshwater ecosystems in Bulgaria is proposed, based on 389 multimethodological and multihabitat fish sampling occasions. Referent-type communities have been determined for 33 types of recognized water bodies. Adapted zonation of Illies is a rough estimation of the real distribution of fish assemblances in the country; moreover, sensitive and/or endemic species are generally of restricted distribution and abundance. In view of the lentic ecosystems, they can be divided into salmonid and cyprinid, at approximately 1500 m above sea level. Full article

(This article belongs to the Section Biology and Ecology)

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