Uptake of copper complexed to EDTA, diaminoethane, oxalic acid, or tartaric acid by neon tetras (Paracheirodon innesi).

Uptake of copper complexes by fish was studied by exposing neon tetras (Paracheirodon innesi) to solutions containing different concentrations of copper complexed to EDTA, diaminoethane, oxalic acid, or tartaric acid, while other copper species were kept at low and constant levels. The distribution of the copper species in the solution was quantified using chemical equilibrium modeling. It was found that the presence of the organic ligands studied could reduce, but not totally eliminate, the uptake of copper by fish. The rate of the additional uptake besides the contribution of free copper depended on the conditional stability constant of the copper complexes.