Effects on Aquatic Organisms Copper sulfate is very toxic to fish. Even at recommended rates of application, this material may be poisonous to trout and other fish, especially in soft or acid waters. Its toxicity to fish generally decreases as water hardness increases. Very small amounts of this material can have damaging effects on fish. Permits are being required in some situations for application of copper sulfate to water bodies.
Copper sulfate is toxic to aquatic invertebrates, such as crab, shrimp and oysters.
Copper sulfate and similar fungicides have been poisonous to sheep and chickens on farms at normal application rates. The lethal concentration fifty, or LC50, is that concentration of a chemical in air or water that kills half of the experimental animals exposed to it for a set time period. Copper is considered to be among the more mobile of the heavy metals in surface environments. Copper is bound, or adsorbed, to organic materials, and to clay and mineral surfaces. The degree of copper adsorption to soils depends on the level of acidity or alkalinity of the soil.