Determination of Median Lethal Concentration (LC50) and Bioaccumulation of Copper in Labeo rohita and Cirrhinus mrigala Based on Acute Toxicity Test

Acute Toxicity of Cu at Four Developmental Stages of Two Freshwater Fishes

Abstract

Widespread application of Copper (Cu) sulfate (CuSO₄) leads to significant health risks to various aquatic organisms. The present study aims to determine the Median Lethal concentration over 96 hours (hrs) period (LC₅₀/96h) and the accumulation of copper sulfate (CuSO₄.5H₂O) in tissues across at four aged and developmental stages of Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigala). The determination of LC₅₀/96h values for Cu sulfate was conducted across embryonic and larval, swim-up fry, advanced fry, and fingerling stages for both Labeo rohita and Cirrhinus mrigala. The resulting LC₅₀/96h values were 0.37 ppm, 0.75 ppm, 1.07 ppm, and 1.34 ppm, 0.48 ppm, 0.94 ppm, 1.36 ppm, and 1.52 ppm for Mrigal, respectively. To assess the bioaccumulation of Cu, 1gram samples from the first three developmental stages (Embryonic and larval, Swim-up fry, and Advanced fry) underwent digestion, while at fourth fingerling stage, five tissues (namely gills, liver, kidney, skin, and muscle) were selected and digested. The results indicated a bioaccumulation order of Cu as fingerling > advanced fry > swim-up fry > embryonic and larval stages for both species. Further, results revealed that at the fingerling stage, the bioaccumulation order of Cu in Labeo rohita was observed as gills > liver > skin > kidney > muscle tissues, while in Cirrhinus mrigala, it was liver > gills > kidney > skin > muscle tissues. This study explores the importance of understanding of developmental stage-specific responses to Cu exposure. Moreover, this research provides essential baseline information for establishing permissible Cu levels across developmental stages in freshwater fish species.