Acute toxicity of nitric acid to fingerling rainbow trout (Salmo gairdneri).

The acute toxicity of nitric acid to fingerling rainbow trout was measured in 7 day bioassays at 11 degrees C. The LC50 was about pH 4.0. Fish which died at low pH (3.0-4.0) exhibited classical symptoms of acid toxicity. Comparison of our results with other toxicity measurements suggests that nitric acid is intermediate in toxicity between H2SO4 and HCl at pH 3.0 and less toxic than either acid at pH 3.3 and above.