Antibiotic Usage and Oxytetracycline Residue in African Catfish (Clarias gariepinus in Ibadan, Nigeria)

The practice of antimicrobial usage in African catfish (Clarias gariepenius) production and the presence of antimicrobial residue in catfish in Oyo State were investigated by cross sectional study. Twenty commercial fish farmers were interviewed using interviewers administered semi-structured questionnaire on the pattern of antibiotic usage, knowledge of occurrence and risks of antimicrobial residues in catfish produced for public consumption. In addition, 165 samples of Clarias gariepenius were obtained from ready to eat fish restaurants and farms for screening for antimicrobial residues using Premi®Test kit while oxytetracycline residue was determined by high performance liquid chromatography (HPLC). The results showed that majority (95%) of the respondents frequently administered drugs (in feed and water) to their fish without veterinary prescription and not observing withdrawal period. Oxytetracycline is the commonly used, extra-label drug usage were frequently practiced. Ninety eight (61.3%) liver and 84 (52.5%) muscle of catfish screened contained detectable antimicrobial residues, while 62 (38.8%) liver and 48 (30.0%) muscle had oxytetracycline residue by HPLC method. Oxytetracycline concentrations in the positive samples ranged between 234.3 and 987.5 μg kg 1 (mean = 875.32±45μg kg ) in the liver and 22.5 and 553.2 μg kg (mean = 257.2±133μg kg ) in the fillets. Forty 1 1 1 three (26.9%) liver and 30 (18.8%) fillets contained oxytetracycline residues above the Codex Alimentarius Commission established maximum residue limit of 600 and 200 μg kg respectively. This implied that 1 appreciable quantity of catfish consumed in Ibadan, Nigeria posed antibiotic residue risks and food safety consequences. Misuse of antibiotics in aquaculture production without veterinary prescription and control coupled with lack of awareness of the food safety consequences were the contributing factors for the high level of residue violation. Therefore, there is need for veterinary supervision of drug use in fish, residue monitoring and food safety education of producers and consumers.