Paraquat-Induced Acute Toxicity Response in Juvenile African Catfish Clarias gariepinus (Burchell, 1822)

Abstract

The extensive application of Paraquat in agricultural and non-agricultural sectors has led to severe physiological and environmental consequences. Hence, this paper was aimed at investigating the Paraquat-induced acute toxicity response for 98 hours in juvenile African catfish Clarias gariepinus using standard methods. The mean weight and mean total length of the fish were 60.67 ± 0.2 g, and 23.06 ± 0.2 cm. The fish were randomly distributed into a transparent plastic aquarium (22.6 x 18.5 cm). Paraquat was introduced at concentrations of 0.00, 0.4, 0.8, 1.2, 1.6, and 2.0 mg/l into the aquaria with the corresponding percentage mortality for 0, 30, 40, 55, 75, and 100% respectively. The observed behavioral changes and mortality were time and concentration-dependent. Symptoms of toxicity exhibited by the fish include loss of equilibrium, startle responses, hyperactivity, abnormal swimming, hemorrhage, and general restlessness. The median lethal concentration (LC₅₀) estimated by probit analysis was 1.017 mg^-l. The physicochemical parameters of the aquaria were in the following range DO, 3.00 - 5.80 mgL^-1, temperature, 19.75 - 21.90 ^oC, TDS 10.10 - 20.20 mgL^-1, alkalinity 40.80 - 91.00 mgL^-1, and pH, 6.7 - 8.04 respectively. The measured haematological parameters showed a concentration-depending pattern of alterations due to paraquat exposure. The highest haematological parameters such as TWBC, 124.50 ×10⁹L^-1, TRBC, 2.01 ×10¹²L^-1, Tplt, 85.00 ×10⁹L^-1, and LYM, 84 % were recorded in 2.0 mgL^-1 paraquat concentration. This result revealed the toxic effects of Paraquat on juvenile Clarias gariepinus. Hence, the need for its regulation in both agricultural and non-agricultural sectors.