CLINICAL SAFETY OF TETRACYCLINE TREATMENT IN NILE TILAPIA (OREOCHROMIS NILOTICUS)

Abstract

This study aimed to evaluate the clinical safety of tetracycline, administered orally and incorporated into feed, in Nile tilapia (Oreochromis niloticus). A total of 104 tilapia (±100 g) were randomly distributed in 13 tanks with 100 L of water each. The treatments consisted of T0 (control, without tetracycline), T1, T2 and T3 (100, 200 and 400 mg of tetracycline/kg of feed, respectively). Eight fish per treatment were sampled on days 4, 8, 12 and 16 (recovery period). Hematological and serum biochemical analyses and somatic evaluation of liver, spleen and kidney were performed. The results showed no significant changes in hematocrit, MCV, MCH, MCHC, hemoglobin, creatinine, total protein, albumin, cholesterol, triglycerides, and alkaline phosphatase levels. However, a reduction in the number of erythrocytes was observed in the groups treated with 200 and 400 mg, in addition to an increase in AST levels and maintenance of hyperglycemia in the 400 mg group, suggesting dose-dependent effects on hepatic and metabolic physiology. Leukocyte counts and somatic indices were not significantly altered. It is concluded that tetracycline has a satisfactory clinical safety profile at the doses tested, and caution is recommended at higher doses or prolonged treatments.