Challenges and emerging trends in fish vaccine platforms, delivery methods, and field performance for sustainable aquaculture: A scoping review

Abstract

Fish vaccination has been practiced globally for several decades and is increasingly recognized as a cornerstone of sustainable disease management in aquaculture, offering an effective alternative to antibiotic and chemotherapeutic use. This PRISMA‐ScR guided Scoping Review synthesized evidence from 173 peer‐reviewed studies and reports to evaluate vaccine platform efficacy, administration routes, adoption challenges, and emerging directions. The major findings indicate that across laboratory and field trials, multivalent injectable vaccines in salmonids consistently achieved Relative Percent Survival (RPS) values exceeding 80% against bacterial pathogens such as Aeromonas salmonicida and Vibrio anguillarum , contributing to a documented 99% reduction in antibiotic use in European countries' aquaculture sector. Experimental immersion and oral vaccines for warm‐water species such as tilapia and carp demonstrated more variable efficacy, with RPS typically ranging from 50% to 75%, reflecting challenges in antigen delivery and uptake. Economic analyses from industrial salmon and tilapia farming report positive Benefit–Cost Ratios (BCR) ranging from 2.5:1 to 5:1, driven by reduced mortality and improved feed conversion ratio (FCR). However, for small‐ and medium‐scale fish farms in low‐ and middle‐income countries (LMICs), vaccine adoption remains below 15% due to high upfront costs, cold‐chain limitations, and lack of locally validated formulations. Critical knowledge gaps persist, including insufficient field validation of vaccine efficacy under commercial conditions, the absence of harmonized immune assays to enable cross‐study comparisons, and limited understanding of environmental modifiers such as temperature, oxygen, and stress on vaccine performance. Future research should prioritize integrating epidemiological modeling for disease prioritization and developing affordable, thermostable vaccines tailored to LMIC fish species. Addressing these gaps through targeted investment and partnerships will enhance aquaculture resilience, reduce antibiotic dependency, and strengthen global food security.