THE EFFECT OF ACUTE EXPOSURE TO DIETARY CD AND CU ON ORGAN TOXICANT CONCENTRATIONS IN RAINBOW-TROUT, ONCORHYNCHUS-MYKISS

Trout were fed on a commercial diet containing 10 g of Cd or Cu kg/dry weight of food for 28 days to determine whether fish could ingest and accumulate toxicants from heavily contaminated food. Fish initially i ngested either diet, but food regurgitation eventually occurred. Dieta ry Cd was more toxic than Cu, causing 14 compared to one mortality. Ca dmium deposition in internal organs and impaired copper metabolism con tributed to mortalities in the Cd-exposed group. Dietary Cd accumulate d in the gills, liver, kidney, and muscle. Oral doses of Cu appeared i n the gill, liver, and muscle; but not significantly in the kidney. Th e highest toxicant concentrations were recorded in the gill and liver, while contamination in the muscle was lower than in other tissues exa mined. Only limited amounts of Cd and Cu were excreted via the body su rface mucus. This study suggests that fish will ingest heavily pollute d food until toxicity occurs. Wild fish may therefore be at risk from contamination via the diet after pollution incidents.