Effects of copper, cadmium, lead, and arsenic in a live diet on juvenile fish growth

The effects of diet-borne copper, cadmium, lead, and arsenic on juvenile fish were evaluated using a live diet consisting of the oligochaete Lumbriculus variegatus. In 30 d exposures, no effects were observed on the growth and survival of rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), and channel catfish (Ictalurus punctatus) fed diets contaminated with copper [130-310 μg Cu (g dm) ^-1], cadmium [90-540 μg Cd (g dm) ^-1], and lead [850-1000 μg Pb (g dm) ^-1]. However, rainbow trout growth was reduced in a dose-dependent manner for diets contaminated with arsenic [26-77 μg As (g dm) ^-1]. These effects of arsenic on fish growth were accompanied by slower feeding rate, reduced food conversion efficiency, liver cell abnormalities, and fecal matter changes suggestive of digestive effects, and occurred to a similar extent whether the diet was exposed to arsenate or arsenite. Effects from these dietary levels of arsenic, and the absence of effects from these dietary levels of metals, were generally consistent with literature reports using laboratory diets amended with toxicant salts. These results also indicated that reported growth effects on rainbow trout fed diets of invertebrates collected from mining-contaminated areas of the Clark Fork River (Montana, USA) or exposed in the laboratory to Clark Fork River sediments are likely more attributable to the arsenic than the metals in those diets.