Effects of short-term dietary oxytetracycline treatment in the farmed fish Piaractus mesopotamicus.

This article investigates the ecotoxicological effects of short-term dietary treatment with oxytetracycline (OTC), a widely used antibiotic in aquaculture, on the freshwater farmed fish Piaractus mesopotamicus (pacú). Juvenile fish were fed diets containing either pure OTC (ATB1) or a commercial OTC formulation (ATB2) at therapeutic doses for 10 days, followed by a 21-day withdrawal period. The study found that OTC exposure, particularly from the commercial formulation, induced oxidative stress evidenced by increased catalase and glutathione S-transferase activities in various tissues, altered hematological and biochemical parameters such as decreased hematocrit and increased glucose levels, and reduced alkaline phosphatase activity in the liver. Differences in biomarker responses between pure and commercial OTC treatments suggest that unknown compounds in the commercial formulation may influence toxicity or bioavailability. The authors emphasize the need for further research on antimicrobial impurities and stricter quality control in aquaculture antibiotics to ensure sustainable and safe fish production.