By K.G. Waiwood, F.W.H. Beamish
Water Research, Volume 12, Issue 8, 1978, Pages 611-619, ISSN 0043-1354, DOI: 10.1016/0043-1354(78)90141-0.

Critical swimming velocities of Salmo gairdneri at 12[degree sign]C were determined in different combinations of copper; pH and hardness. Measurements were made after exposure for 0.5, 5, 10, and 30 days. When copper was not applied, hardness, pH and exposure time had no appreciable effect on critical performance. Copper had the greatest effect on swimming performance at 5 days of exposure. At pH 7.5-8.0, recovery from the initial depression was complete after 10 days of exposure, but critical swimming performance did not return to control levels in pH 6.0 treatments. For any given hardness, copper had a greater effect on critical speed at low than at high pH. A given copper treatment had a more pronounced effect at low than at high hardness.
No distinction could be made among total, soluble, or extractable copper but predicted concentrations of 6 specific cupric ions varied with pH and hardness. Of these copper species, only Cu2+ and CuOH+ were found to be related significantly to critical performance.
Oxygen consumption of trout was determined in different combinations of copper and pH. In the presence of copper the maximum oxygen consumption decreased and the energy expenditure for a given swimming speed increased.
The above observations are discussed in relation to reported toxic actions of copper.

More details...