Acute Toxicity of Zinc to Common Freshwater Fishes of Lithuania

Laboratory tests were conducted on fishes of 5 species common to Lithuania to estimate their sensitivity to acute toxicity of zinc. The species tested were rainbow trout (Oncorhynchus mykiss), three-spined stickleback (Gasterosteus aculeatus), roach (Rutilus rutilus), perch (Perca fluviatilis) and dace (Leuciscus leuciscus). Rainbow trout was obtained from a fish farm, and other species were collected in natural waters. The tests were conducted in the laboratory under flowthrough conditions and two tests were performed on each species. The mean pH values of the test water were within the range of 7.9-8.1, hardness from 270 to 300 mg/litre as CaCO3. The 96-hour median lethal concentration (96-hr LC50) values obtained from the tests ranged from 3.79 to 11.37 mg Zn/litre. The sequence of sensitivity of the tested fish species was found to be as follows: rainbow trout > three-spined stickleback > perch > dace > roach.