Acute toxicity of glyphosate-based isopropylamine formulation to juvenile African catfish (<i>Clarias gariepinus</i>)

Abstract

The formulation of glyphosate composed of Isopropylamine salt (41 % wt) is widely used as herbicide both in the terrestrial and aquatic environment. This study examined the toxicity of the surfactant Isopropylamine salt of glyphosate herbicide to post juvenile African catfish (Clarias gariepinus).. This experimental design was based on the standard Total Residual Chlorine (TRC) method with interval time of 24, 48, 72 and 96 hrs. Gulping of air, restlessness, surface to bottom movement, sudden quick movement and excessive resting at the bottom were abnormal behaviour observed in the exposed fish. Mortality of C. gariepinus increased (p<0.05) with an increase in glyphosate concentration. The results showed that the 96h LC₅₀ value of glyphosate was 300 mg/L while the maximum allowable concentration (MAC) of this toxicant is 30.0 mg/L. The effect of the toxicant on C. gariepinus was both time and concentration-dependent.

Keywords: Acute toxicity, Clarias gariepinus, Glyphosate, LC₅₀, Mortality