Valorization of Ripe Plantain Peel Waste in Aquaculture: Acute Toxicity, Behavioural Responses and Tissue Alterations in Juvenile African Catfish (Clarias gariepinus) (Burchell, 1822)

Abstract

This study evaluated the acute toxicity, behavioural responses, water-quality variations, and histopathological alterations in the gills and liver of juvenile Clarias gariepinus exposed to an ethanolic extract of ripe plantain (Musa paradisiaca) peels. Fish were exposed to extract concentrations of 0, 20, 25, 30, and 35 mg/L for 96 hours under static bioassay conditions. Behavioural responses, mortality, and water-quality parameters were monitored throughout the experiment, while histological examinations of the gill and liver tissues were conducted at the end of the exposure period. Exposed fish exhibited concentration-dependent behavioural abnormalities, including erratic swimming, respiratory distress, vertical erection, air gulping, and escape attempts. Mortality increased progressively with increasing extract concentration, with the highest mortality recorded at 35 mg/L. The 96-hour LC₅₀ was estimated at 35 mg/L (log concentration = 1.54), indicating moderate toxicity. Significant variations were observed in dissolved oxygen, pH, temperature, and conductivity across the concentrations and exposure periods. Histological examination of the gills revealed predominantly normal architecture, with only mild focal epithelial degeneration and haemorrhage at 20 mg/L. Liver tissues exhibited concentration-dependent alterations, including macrovesicular steatosis, inflammatory-cell infiltration, cytoplasmic vacuolation, vascular congestion, and sinusoidal congestion. The findings indicate that the ethanolic extract induced physiological and histopathological stress in juvenile C. gariepinus at higher concentrations, with the liver showing greater responsiveness than the gills. However, the absence of severe tissue necrosis suggests low-to-moderate toxicity within the tested concentration range. These results provide baseline information for evaluating the potential utilisation of ripe plantain peel-derived products in aquaculture.