Editorial - Oral Immune-Enhancing Research in Fish

Aquaculture is recognized globally as the fastest growing food-producing sector for human consumption (1). However, to satisfy increasing international demand, it is predicted that current production must be doubled by 2030 while improving the biosafety protocols (2). Such an expansion will necessarily involve implementing innovative actions in aquaculture production while also targeting effective health control measures and considering animal welfare. Diet, environment, and host genotype have been repeatedly demonstrated to play an essential role in defining the fish gut composition (3). However, only a few studies have examined the association between disease severity and degree of dysbiosis in fish. Likewise, the management of pathogens and parasites remains a sustainability challenge industry-wide due to poor understanding of the associated fish immune mechanism across species, and the effects of climate change on aquaculture remain uncertain and complex to validate (4). While these concepts are not necessarily new, applying modern high-throughput sequencing approaches and state-of-the-art immune techniques will accelerate our understanding of the complex trophic (e.g., prokaryotic, eukaryotic) structures, the host recognition systems within aquaculture species and systems, and the effect of an intervention on eventual health outcomes allowing aquaculture to benefit from parallel advances in related disciplines (5). Among the latest therapies developed, orally administered health promoters have demonstrated a strong ability as critical mediators in enhancing the fish immune system. However, the interaction between each element per fish species is highly complex and not always homogeneous along the different developmental stages. Therefore, to assess the expected potential immunological promotion and enhancement capacity, the use of dedicated, robust, and innovative molecular tools accompanied by keen strategies of analysis devoted to elucidating the mode of action for the tested compounds are required. By collating evidence, eleven exciting research papers written by 79 authors in our Research Topic entitled “Oral Immune-Enhancing Research in Fish” are presented in this ebook. Together, they will provide a platform of discussion in the advancement of the actual knowledge and understanding beyond the immediate immune effects and the corresponding immune mechanisms in fish fed with functional feed additives, live supplemented feed, or even exposed to oral pollutants that stimulates a differential immune response in the animals under experimental or fish farm settings.