Absence of overt toxicity from feeding the flavonol, quercetin, to rainbow trout (Salmo gairdneri).

The toxicity of the plant flavonol, quercetin, to rainbow trout (Salmo gairdneri) was investigated. Quercetin, which had been confirmed to be mutagenic in the Ames Salmonella/mammalian microsome test, was fed to trout at levels of 1 or 5% in the diet for 8 months. Survival, growth and feed conversion efficiency, selected haematological parameters and the relative weights of heart, liver and spleen were unaffected by the ingestion of quercetin, and there were no histopathological changes in any of the tissues examined.