The Toxicity of Ethanolic Extract of Alchornea cordifolia Leaf on Clarias gariepinus Fingerlings

Acute toxicity effects of ethanol extract of Alchornea cordifolia leaf on Clarias gariepinus fingerlings was investigated over a 96hr exposure period as a potential organic piscicide. A static toxicity bioassay was performed after preliminary trial tests (range-finding test) were conducted. Five hundred (500) post-fingerlings of Clarias gariepinus were distributed randomly in duplicate concentrations. The test fishes were treated with concentrations of 1.31, 1.96, 2.97, 4.45 and 6.67 mg/1 of Alchornea cordifolia. Exposure to the plant toxicant caused visible behavioural changes which include erratic swimming, air gulping, discolouration, loss of body equilibrium, the settlement at the bottom and death. Mortality was recorded in some of the exposed fish while the LC50 lethal concentration of 2.138 mg/1 was established and safe concentration was established as 0.2138 mg/l. There were significant changes (p˃0.0.5) in the water quality parameters except for electrical conductivity, the unstable behaviour of the fish must have been as a result of irritation from the toxicant. Therefore, the use of A. cordifolia in fish harvesting should be regulated and not allowed to gain access unnecessarily into the aquatic ecosystem and regulatory bodies should maintain the safe concentration of 0.2138 mg/l.