1H NMR metabolomic responses correlated to meat quality of Nile tilapia (Oreochromis niloticus) reared under combined dietary salt and water salinity conditions

Freshwater scarcity has driven interest in culturing euryhaline species such as Nile tilapia ( Oreochromis niloticus ) in saline systems for sustainable aquaculture. This study examined the combined effects of dietary NaCl (2.5 % and 5.0 %) and water salinity (0, 15, 25 ppt) on tilapia muscle metabolome and meat quality using 1 H NMR metabolomics. Fish fed 5.0 % NaCl at higher salinities showed reduced muscle protein, increased salt, elevated TBARS, and lower TVB-N ( P < 0.05). Under these conditions, water-holding capacity improved, while hardness and chewiness decreased, suggesting softer texture. Sensory evaluation showed no differences in consumer acceptance ( P > 0.05). Metabolomics revealed ten key metabolites (e.g., carnosine, tyrosine, betaine, glycogen, lactate) and seven enriched pathways linked to osmoregulation and energy metabolism. Multivariate analyses indicated dietary salt exerted greater influence than water salinity, highlighting the need for feed adaptation. Overall, results demonstrate physiological trade-offs of salinity adaptation and identify potential biomarkers for meat quality in saline aquaculture.