Kaluga is a large predatory fish of the sturgeon species. Its length is up to 6 m, weight up to 1000 kg, usual weight 150-400 kg. Has coloring from gray-green up to black. There are two kinds of Kaluga: the first kind comes from Amur estuary on spawning to the Amur river and the second one constantly inhabits the Amur river. Kaluga is endemic of the Amur river. You can not find this kind of fish in any other place of the world. Spawning time is May - June. It lives up to 50 years. The population is supported by cultivation.