Dear Colleagues,

With the worldwide increase in aquaculture production and the associated trend of increasing fish culture density and the number of farms, the study of fish diseases has become a crucial component of the entire productive system due to the potential economic and ecological risks involved. Despite numerous studies focusing on the etiological agents responsible for fish infectious diseases, modern trends aim to investigate and comprehend the interrelationship between pathogen, microbiome, immune system, and endocrine regulation. The occurrence of fish diseases is significantly influenced by both environmental and endogenous factors, which, in turn, can be affected by the complex interactions of the microbiome, immune system, and endocrine factors.

Regarding the immune system, understanding its relationship with infectious diseases is important for developing effective prevention and treatment strategies, identifying new therapeutic targets, and gaining insights into disease pathogenesis. Coincidently, aquaculture has been transformed into an environmentally friendly practice that minimizes the abuses of veterinary medicines and the spread of antimicrobial resistance, especially mitigating the influence on wildlife and ensuring the safety of human food supplies. Furthermore, various physiological aspects of the endocrine system, including nutrition, growth, reproduction, and stress, can influence the progression of infection and pathology. On that note, stress is known to play a key role in the bidirectional communication between the immune system and the endocrine system, which can also be regulated by gut microbiota. Considered to be a neglected endocrine organ, the microbiota also participates in a deep communication with the immune system to maintain homeostasis and health.

The potential of these relationships is enormous for nourishing both basic research and industry. From developing more efficient vaccines and other immunological agents to better understanding the opportunistic strategy of pathogens due to immune suppression mediated by the endocrine system and microbiome dysbiosis, there are still significant gaps in our knowledge that should be addressed in the coming years.

Thus, the objective of this Special Issue is to present recent research and reviews on infectious diseases in fish, covering the topic of how these diseases are related to the immune response, endocrine factors, and microbiota regulations.

Dr. Álvaro Fernández-Montero
Dr. Yang Ding
Guest Editors

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• fish
• aquaculture
• infectious diseases
• immune response
• immunology
• microbiota regulation
• microbiome
• stress
• endocrinology