Caspian Sea
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans.
Caspiosoma caspium
Caspiosoma caspium is a species of Ponto-Caspian goby native to the deltas of rivers inflows to the north-western Black Sea: Dnieper up to Berislav, also in the Dnieper-Bug Estuary and Berezan Estuary, Danube, Dniester with the estuary, Cuciurgan Reservoir. Found in the delta of the Don River, Volga, central and northern parts of the Caspian Sea and rivers flowing into the Sea of Azov. It can be found at depths of from . This species can reach a length of TL. It is currently the only known member of its genus.