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

Abstract

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 0.13
9.17 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.