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.

Keywords

• Paraquat; Toxicity; Clarias gariepinus; Aquatic environment