Toxicity of fipronil insecticide on the early life stages of Co-lossoma macropomum (gamitana)

The present study was aimed to determine the lethality of the insecticide fipronil on two early life stages, post-larvae, and fingerling, of Colossoma macropomum, by determining the lethal concentration 50 (LC₅₀ ). Five nominal concentrations (0.12; 0.165; 0.21; 0.255 and 0.30 mg/L) and a control in 4 replicates per treatment for 48 hours of exposure were used for the post-larvae; and other nominal concentrations (0.22; 0.27; 0.34; 0.43 and 0.54 mg/L) and a control in 3 replicates per treatment for 96 hours of exposure were used for the fingerling stage. The LC₅₀ value was calculated as 0.22 mg/L and 0.33 mg/L for the post-larvae and fingerling stages, respectively. In addition, the maximum concentration that causes no mortality (MCNM) and the minimum concentration that causes mortality (MCM) for the post-larvae stage were determined as 0.12 and 0.15 mg/L, respectively; and 0.16 and 0.22 mg/L for the fingerling stage, respectively. C. macropomum showed erratic swimming, spasms in the region of the peduncle, caudal fin, and accelerated opercular movement in both life stages. The LC₅₀ values calculated in the present study are considered “highly toxic” for the early stages of life of this non-target organism, suggesting that C. macropomum may be a sensitive species to fipronil insecticide.