Molecular Stress Biomarkers in Aquaculture: A Systematic Review.

This systematic review of the literature aimed to explore the molecular biomarkers used for the detection of stress in the aquaculture sector over the last decade. Relevant studies were retrieved from the Web of Science, Scopus and PubMed databases, which were last searched on 13 June 2025. After screening according to predefined eligibility criteria and PRISMA 2020, 64 peer-reviewed original research articles published between 2015 and 2025 were included. The included studies were qualitatively synthesised. These studies evaluated molecular biomarkers of stress across 31 fish species, with Salmo salar being the most frequently studied, followed by Oncorhynchus mykiss. China, Spain and Canada contributed the largest numbers of included studies. In total, 20 different stressors were identified. Temperature was the most frequently investigated stressor, followed by stocking density, hypoxia and exposure to various chemicals. Publication activity has grown over the last decade, with a clear increase since 2020. This systematic review was conducted to integrate current knowledge and emerging evidence on molecular markers in teleost fish, aiming to provide a comprehensive understanding of both established biomarkers and novel molecular candidates identified through recent studies. Although considerable heterogeneity was observed among fish species, stress protocols and biomarker assessment methods, the evidence supports the growing value of integrated biomarker approaches for stress assessment in aquaculture. Overall, the evidence supports integrated, context-specific biomarker approaches that combine molecular endpoints with established physiological indicators to improve stress assessment in aquaculture.