Copper Toxicity on Growth and Reproductive Potential in an Ornamental Fish, Xiphophorus helleri

Abstract

The effect of copper toxicity on growth, gonad development and reproductive performance in an ornamental fish, Xiphophorus helleri was studied for 140 days. The 96 h LC50 value of copper for X. helleri was 0.361 mg•l-1. Exposure of animals to sublethal concentrations of copper reduced the rates of food intake and conversion and conversion efficiency ; also reproductive indices like gonad weight, gonadosomatic index and fertility showed significant reduction in relation to copper concentration. Metabolic parameters like oxygen consumption and opercular beat, on the other hand, exhibited opposite trend. Reduction in the rate and efficiency of conversion negatively reflected on the reproductive performance of experimental fish. Test fish reared in tap water (control) and lowest concentration of copper (0.04 ppm) bred two times and released more number of young ones than other exposures. Control individual released 228 young ones whereas those exposed to 0.04, 0.08 and 0.12 ppm copper released only 72, 29 and 17 young ones during the experimental period of 140 days. Sublethal concentrations of copper, eventhough, reduced the number of young ones production, did not cause mortality. Vertebral deformities (scoliosis) particularly tail curvature was observed in male X. helleri exposed to the highest concentration of copper.