The Beluga /bəˈlu:ɡə/ or Great sturgeon (Huso huso) is a species of anadromous fish in the sturgeon family (Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and formerly in the Adriatic Sea. Going on maximum size, it is the third most massive living species of bony fish. heavily fished for the female's valuable roe, known as beluga caviar, wild populations have been greatly reduced by overfishing and poaching.