Physiological responses in common carp (Cyprinus carpio) exposed to oxytetracycline

This study investigated the physiological responses of Cyprinus carpio, a globally distributed freshwater fish of considerable ecological and economic importance, following dietary exposure to oxytetracycline (OTC), a tetracycline-class antibiotic extensively used in aquaculture. Juvenile fish (5.3±0.7 g) were fed for 45 days with a formulated diet containing 35% crude protein and supplemented with graded concentrations of OTC (25, 50, 75, and 100 mg/kg diet) at a feeding rate of 5% body biomass. Dietary OTC exposure resulted in pronounced alterations in growth performance, respiratory metabolism and ammonia excretion, indicating disruption of normal physiological homeostasis. The dose-dependent responses observed in the present study highlight the sensitivity of these physiological parameters and suggest their potential utility as reliable biomarkers for assessing sublethal effects and environmental risks associated with antibiotic contamination in aquatic ecosystems.