The effects of copper and cadmium in single or co-exposure (each at the concentration of 0.2 mg×dm^-3, and in mixture - 0.1 mg×dm^-3) on growth of common carp larvae (in terms of body length and perimeter area) during the first 30 days post hatching were evaluated. Body length increased in a similar rate during the entire experimental period, while the increase of body perimeter area became faster after the shift into exogenous feeding, and then during swim bladder inflation. Copper was more toxic to the fish comparing cadmium or a mixture of both metals which indicates a possible antagonism of cadmium against copper toxicity. Body perimeter area was a more sensitive indicator of heavy metal intoxication compared to body length, and may be used as an approximation of body mass for very small fish that cannot be accurately weighed alive.