Ceftiofur and flunixin meglumine-induced acute behavioral and biochemical alterations in Nile-tilapia (Oreochromis niloticus).

The widespread use of veterinary pharmaceuticals has increased the occurrence of drug residues in aquatic environments, raising concerns about their effects on non-target organisms. This study evaluated the behavioral and biochemical effects of acute exposure (96 h) to ceftiofur (CEFT, 1.7 μg L-1) and flunixin meglumine (FLUNI, 100 μg L-1), alone or in combination, in Nile tilapia (Oreochromis niloticus) fingerlings. Fish were assessed using the Novel Tank Test and the Social Preference Test, followed by the determination of acetylcholinesterase (AChE) activity, catalase (CAT) activity, non-protein thiol (NPT) levels, and thiobarbituric acid reactive substances (TBARS). In summary, acute exposure to CEFT and FLUNI, individually or in combination, induced significant behavioral and biochemical alterations in juvenile Nile tilapia. The treatments promoted anxiety-like behavior, while CEFT increased locomotor activity, an effect partially attenuated by FLUNI during co-exposure. CEFT also impaired social behavior, although this effect was partially reversed by co-exposure with FLUNI. Biochemically, combined exposure promoted brain lipid peroxidation together with increased catalase activity, indicating tissue-specific disturbances in redox homeostasis. These findings demonstrate that veterinary pharmaceuticals, alone or in combination, can disrupt behavioral performance and physiological homeostasis in Nile tilapia, reinforcing the ecotoxicological risks associated with pharmaceutical contamination of freshwater ecosystems.