Levels of Antibiotics in Fish Species from Eleyele River, Ibadan, Nigeria

Antibiotics are commonly used to treat infections in humans and animals, and in aquaculture to prevent bacterial diseases. However, their excessive use in livestock and poultry have led to environmental contamination, particularly in water bodies, raising concerns about food safety and public health. This study investigated the presence of tetracycline, chloramphenicol, and metronidazole in three fish species— Parachanna obscura (Obscure snakehead), Clarias gariepinus (African sharp-tooth catfish), and Oreochromis niloticus (Nile tilapia)—from Eleyele River in Ibadan, Nigeria. Using solid-phase extraction and silica gel clean-up, followed by high-performance liquid chromatography with diode-array detection (HPLC-DAD), antibiotic residues were detected at concentrations ranging from below detection limits to 1311.82 ng/g. Method validation showed high sensitivity, with limits of detection (LOD) between 0.139.17 ng/g and limits of quantification (LOQ) from 0.41–27.78 ng/g. P. obscura and C. gariepinus had significant levels of all three antibiotics, while no residues were found in O. niloticus. The concentrations found exceeded the 0.1µg/g maximum residue limit set by the European Union, indicating a potential health risk for consumers and environmental harm. This study concluded that the fishes from Eleyele River were contaminated with antibiotic residues at levels above international safety standards. It is recommended that routine monitoring be enforced, alongside stricter regulations and public education on responsible antibiotic use in agriculture and aquaculture, to mitigate further contamination and protect public health.