Mysis salemaai is a shrimp-like crustacean in the Mysida order, inhabiting lakes of Ireland and South Scandinavia and brackish waters of the northern Baltic Sea.

It has two pairs of relatively long antennae, associated with rounded antennal plates; large, stalked compound eyes; the thorax covered by a coat-like carapace; a muscular, cylindrical abdomen; and a tail fan featuring a telson with a V-shaped terminal cleft.

Mysis salemaai is a North European species which lives both in fresh and brackish waters.

[2] Mysis salemaai is also common in the Baltic Sea, where it lives in offshore waters of the diluted northern parts of the basin.

The distributions of the two species overlap in the Baltic Sea and some lakes of Sweden, but M. relicta is not found in Ireland.