Histological studies on the effect of phostoxin on African catfish (<i>Clarias gariepinus</i>) juveniles

Abstract

The toxic effects of phostoxin on juveniles of African catfish (Clarias gariepinus) were investigated. One hundred and twenty (120) juveniles of Clarias gariepinus (wt. 25 ± 0.25 g) were allotted into twelve (12) glass tanks (60 cm x 40cm x 40 cm) at ten (10) fish per tank/treatments (A - F) in two replicates based on different concentrations of Phostoxin (0.01, 0.02, 0.03, 0.04 and 0.05 mg/l) used while treatment A serves as control (0.0 mg/l) tank.. The test fish exhibited some behavioural abnormalities such as; loss of reflex, restlessness, colour change, high rate of opercula movement, abnormal swimming and mortality. The histology of the test fish revealed changes in the gills which included erosion of the secondary lamellae, loss of epithelia cells and degeneration of lamellae, alterations observed in the liver tissues fish were visible lesion, necrosis and mild degeneration while the kidneys showed mild degeneration of renal tubules, interstitial congestion, and diffuse tubular degeneration at high concentrations of phostoxin thereby leading to physiological dysfunctions of the test organs. The 96 h LC₅₀ value was observed at 0.025 mg/L. Hence, discharges of phostoxin into the aquatic environment should be restricted.