Abstract Plant extracts have been used in farmed fish to control fish bacterial infection, fish fry predators, to replace chemical pesticides and piscicides. This study was carried out to assess the toxicological effect of methanol fruit extract of L. breviflora in juvenile African catfish ( Clarias gariepinus ). Forty-five (45) juvenile catfish were randomly and equally divided into 9 groups. The first five groups were administered varying concentrations of L. breviflora fruit extracts (25 mg/L, 50 mg/L, 75 mg/L, 100 mg/L, 125 mg/L) and LC 50 was calculated to be 63.9 mg/L. The remaining four groups were labelled A to D. The fish were exposed daily to graded concentrations of L. breviflora : Group A (Control), Group B (6.25 mg/L), Group C (12.5 mg/L) and Group D (25 mg/L) for 14 days. Blood samples of exposed fish showed significant decreases in the red blood cell count, packed cell volume, haemoglobin concentration, mean corpuscular volume, and mean corpuscular haemoglobin. The histology results show erosion of the epidermis and hyperplastic alarm cells in the skin, areas of diffuse vacuolation, periportal degeneration and necrosis in the liver, mild degeneration of the lamella core, congestion of the submucosa and expanded lamella core in the skin. The plant extract can therefore be recommended for use at concentrations < 10 mg/L.
Anifowose et al. (Sun,) studied this question.