Serum biochemical reference intervals in farmed greater amberjack (Seriola dumerili): Variation across production periods

Greater amberjack ( Seriola dumerili ) is an emerging high-value species in Mediterranean aquaculture; however, effective health management is constrained by the lack of species-specific clinical pathology benchmarks. This study established serum biochemical reference intervals (RIs) for clinically healthy, farmed S. dumerili under Adriatic cage-farming conditions and evaluated temperature-associated seasonal variation across three production periods (July, December, and March). Blood samples were collected from clinically healthy fish in each period, and 17 biomarkers representing metabolic substrates, enzymes, electrolytes, and minerals were quantified. The July cohort, corresponding to the optimal growth period, was used to calculate central 95% reference intervals (2.5th–97.5th percentiles). Comparison revealed pronounced physiological modulation across multiple biomarkers. Glucose concentrations were consistently elevated in winter and spring relative to the summer baseline, whereas phosphate levels were markedly reduced. Additional seasonal shifts were observed in enzymatic activity, lipid metabolism, and electrolyte balance, reflecting broad environmental influences on physiological status. These findings demonstrate that biochemical profiles in S. dumerili are strongly temperature-associated and seasonally dependent and highlight the limitations of single-temperature reference intervals. The integration of seasonal-temperature framed RIs provides a robust framework for improving diagnostic interpretation and supporting proactive health management in greater amberjack aquaculture.