Abstract

Abstract | The acute toxicity, determined by the LC50+ lethal concentration of a tertiary combination comprising lead (Pb), nickel (Ni), and cadmium (Cd) was assessed on two freshwater fish species, Catla catla and Labeo rohita, employing probit analysis. Over a period of 90 days, mortality served as the primary toxicity criterion. The experiments were conducted under consistent conditions of pH (7), temperature (28.00.00°C), and water hardness (198.00 mgL-1), with three replicates for each dosage in the tests. Significant variations were noted in the LC50 values and lethal responses for both fish species. Catla catla exhibited mean LC50 and lethal concentrations of 55.78±0.55 and 80.17±0.40mgL-1, respectively, while Labeo rohita showed values of 63.92±2.48 and 102.07±0.50mgL-1. Labeo rohita demonstrated higher sensitivity in terms of 96-hour LC50 compared to Catla catla, whereas Catla catla exhibited greater sensitivity for lethal responses. Correlation and regression analyses revealed significant positive correlations between metallic ion concentrations in the test mediums and carbon dioxide, sodium, potassium, and electrical conductivity. On the contrary, a negative correlation was established between dissolved oxygen levels and both fish species in the test environment. These findings contribute to understanding the differential responses of Catla catla and Labeo rohita to the toxic effects of lead, nickel, and cadmium mixture.