COMPARATIVE ZINC CONCENTRATIONS IN TISSUES OF COMMON CARP AND OTHER AQUATIC ORGANISMS

Zinc concentrations in various tissues of 24 aquatic organisms were me asured. Common carp and crucian carp had extraordinarily high zinc con centrations with mean values of 562 and 634 mu g/(g fresh tissue) resp ectively, in their digestive tract tissues. They had high zinc concent rations (usually > 100 g/[g fresh tissue]) in kidney, gill, skeletal t issues, and spleen, which were not seen in other species. Concentratio ns of Cu, Na, K, Ca, and Mg in digestive tract tissues of common carp and several freshwater fish were found to be similar. High zinc was fo und to be specific to common carp. Common carp were reared from fry to adult fish in the laboratory for 937 d and fed on an artificial feed containing 25 ppm zinc. Zinc concentrations in the whole body and dige stive tract tissue of the fish were found to be consistently high thro ughout the period. The anterior portion of the digestive tract tissue of common carp had the highest zinc concentration, 1590 mu g/(g fresh tissue), which decreased gradually to the posterior portion, at about 500 mu g/(g fresh tissue).