Acute toxicity of copper, zinc and manganese in single and mixed salt solutions to juvenile longfin dace, Agosia chrysogaster

The acute toxicity of copper, zinc and manganese and copper‐zinc and copper‐manganese mixtures were determined for juvenile longfin dace, Agosia chrysogaster in hard water bioassays (mean=218 mg 1−1 CaCO3). Copper‐zinc was the most lethal toxicant (96‐h L.c.50= 0.21 mg 1−1 copper and 0.28 mg 1−1 zinc) and exhibited a more than additive toxicity which was in contrast to the additive toxicity of copper‐manganese mixtures (96‐h L.c.50= 0.45 mg 1−1 copper and 64.0 mg 1−1 manganese). The toxicity of copper (96‐h L.c.50= 0.86 mg 1−1) and zinc (96‐h L.c.50= 0.79 mg 1−1) to the fish was similar but both were considerably more lethal than manganese (96‐h L.c.50= 130 mg 1−1).