TOXICITY OF ETHANOLIC EXTRACT OF COSTUS AFER TO CLARIAS GARIEPINUS FINGERLINGS

Abstract This research intends to evaluate the toxicity of Costus afer and ferret out if it is functional as a plant-based additive in the formation of fish feed. The study was conducted using two replicate (Batch A and B) for 96 hours under controlled laboratory conditions. Five concentrations ranging from 0, 5, 10, 15, and 20 mg/l were prepared from the ethanolic extract of Costus afer for the toxicity test. Experiment was conducted in Akwa Ibom State University, Obio Akpa Campus, Akwa Ibom State between November, 2023 and December 2023. Total number of two hundred fingerlings were for the studies. One hundred fingerlings were used for range findings test and the left over for the actual toxicity test. Prior to commencement of the toxicity test, experimental fish were allowed to acclimatize. Each of the ten plastic aquaria was stocked with ten Clarias gariepinus. The prepared plant extract at varying concentration was added to each stock aquaria and allowed to stand for 96 hours for mortality examination. Gills tissues were isolated from the fish samples in each of the concentration after 96 hours for histopathological examinations. The experimental fish showed differential percentage mortalities with toxicant concentrations. The 96 hours LC50 for C. gariepinus for both batches (A and B) was given at 20.5 m/l representing a log transformed concentration of 1.31 mg/l. The results of the present study indicate a concentration-dependent pattern of mortality, with significant reduction observed over time of exposure. Experimental groups exposed C. afer exhibited pathological changes in the gills and behavioral abnormalities. From the findings, it is observed that extract obtained from C. afer is toxic dependent on concentration to aquatic life and can be used at low concentration as a plant-based additive in the formulation of fish feed.