This research investigated the effect of Ichthyotoxic Plant Milletia grifoniana Baill leaves extract on African Catfish Clarias gariepinus under static bioassay laboratory conditions. The 24hrs, 36hrs, 48hrs, 72hrs, and 96hrs LC50 were 2.5mg/l, 2.3mg/l, 1.8mg/l, 1.5mg/l, 1.2mg/l respectively, with the range of maximum admissible concentration (MATC) were 0.25 – 0.025mg/l, 0.23 – 0.023mg/l, 0.18 – 0.018mg/l, 0.1 – 0.015mg/l, 0.12 – 0.012mg/l respectively. The mortality rate in the Milletia grifoniana is concentration dependent, the higher the concentration of toxicant the higher the mortality of fish. Mortality increased with increasing concentration of the extract showing a dose-dependent relationship. Fish showed initial disturbed swimming movements, rapid opercular movements, loss of balance incessant gulping of air, and fish settling at the bottom motionless with slow opercular movements. There were no obvious changes in fish behaviour in the lower concentrations. The abnormal behaviors displayed by the fish increased with increasing concentrations of Ichthyotoxic PlantsMilletia grifoniana(leaves) in water and time of exposure. Histopathological examination of the gill, liver and kidney of the treated fish showed, The Milletia grifoniana shows severe effect on the skin layer with severe superficial spreading of melanoma (M) restricted to the epidermis and the dermis contain severe melanin laden macrophages (MLM). The liver cells revealed hepatic tissue with severe ground glass (GG) appearance of the cytoplasm and intra hepatic hemorrhage (IHH). The gill showed severe effect on the gill architecture with hypertrophy of the gill arch, gill filament and aggregate of inflammation (AI), while the kidney revealed severe degeneration of the renal tissue with severe intra renal necrosis (TN) and inflammatory cell aggregate (IC) with tubular atrophy (TA) in same areas. The damage done to these organs as the result of the toxicant correlates with the concentrations of the toxicant in each experimental tank. The result of this study calls for the need to discourage the use of toxic plants for catching fish in Nigeria water bodies
Keywords: African Catfish (Clarias gariepinus); Behavioural responses, Aqueous Extract., Ichthyotoxic Plant, Milletia grifoniana Baill
