The Kaluga (Huso dauricus) is a large predatory sturgeon found in the Amur River basin. Also known as the river beluga, they are claimed to be the largest freshwater fish in the world, with a maximum size of at least 1,000 kg (2,205 lb) and 5.6 m (18.6 ft). Like the slightly larger Beluga, it spends part of its life in salt water. Unlike the Beluga, this fish has numerous nail-like teeth in its jaws, and feeds on salmon and other fish in the Amur by hunting them.
The Kaluga has been hunted to near extinction for its valuable roe and in spite of constant anti-poaching patrols, poachers still continue to catch the fish. Fishing for Kaluga anywhere in the Amur river is an offense punishable by law. Kalugas are known to have an aggressive nature and there are instances of them toppling fishing boats and drowning fishermen, although there is no concrete evidence of them assaulting or hunting people. Local fishermen have suggested that the Kaluga can grow well up to twenty feet in length and can weigh around 1500 kilos. The Kaluga is one of the biggest of the sturgeon family.