Toxicity Effect of Delsate® Herbicide on Serum Electrolyte Balance of African Catfish Clarias gariepinus (Burchell, 1822)

Abstract

Toxicity effect of delsate^® herbicide on serum electrolyte balance of fresh water African Catfish, Clarias gariepinus adults was monitored for 96 hours. The concentrations of toxicant tested were 0.5 mgL^-1, 1.0 mgL^-1, 1.5 mgL^-1, 2.0 mgL^-1 and 2.5 mgL^-1. The 96 hours LC₅₀ obtained for C. gariepinus with mean weight (661±0.1 g) and standard length (23.5±0.4 cm) was 0.14 mgL^-1. The electrolyte examination indicated that fish were not able to maintain osmotic balance, nerve impulse contraction and gaseous exchange as a result of delsate exposure. There was a notable variation in potassium activity which might be as a result of much accumulation of delsate and signs observed were symptoms of anorexia, convulsions and tetany. The level of Ca²⁺ exposed to delsate for 96 hours decreased significantly in relation to respective control and indicated that exposed fish could loss its balance in the environment and were not able to maintain their integrity and muscle contraction through their gills. The fish suffered from renal impairment, dehydration and hypernatremia/ hyponatremia, seizures and muscle spasms. The results obtained in this study showed that C. gariepinus is sensitive to delsate thus its application near fish farm or in agricultural field close to aquatic environment should be discouraged.

Key Words: Toxicity, delsate, total electrolyte balance, LC₅₀ and osmotic balance