Features of osmotic and ionic regulations in Russian sturgeon (Acipenser güldenstädti Brandt).

The osmolality of blood serum of one group of Russian sturgeon fished out in Southern Caspian Sea was the same as their habitat, the other group of sturgeons had a serum osmolality several per cent lower than that of sea-water in this part of the Caspian Sea. Ion concentrations in blood serum in sturgens were similar in fresh water and the Caspian Sea. The feature of the Russian sturgeon's kidney is intensive potassium secretion and a comparatively low level of magnesium secretion.