Effects of exposure to sublethal levels of cadmium upon water‐electrolyte status in the goldfish (Carassius auratus)

Goldfish were exposed to sublethal levels of cadmium (means of 44.5 and 380 μg Cd ++ /l) for periods of 25 and 50 days, and their water‐electrolyte status evaluated by reference to plasma and muscle levels of sodium, potassium and chloride and muscle water content. Significant changes in plasma chloride, tissue potassium and tissue water content were observed after 25 days in both test solutions. Specimens held at the more dilute cadmium concentration were apparently able to compensate for most of the initial cadmium effect and, after 50 days exposure, were characterized only by a continuing depression in plasma sodium level. This suggests that the cadmium MATC value for this species under the conditions employed is probably less than 45 μg Cd ++ /l. Goldfish exposed to 380 μg Cd ++ /l for 50 days exhibited significant deviations in plasma sodium and chloride levels as well as in tissue sodium and water content, and these parameters may provide useful indices of cadmium effects at sublethal concentrations.