Arctic cod

Arctogadus glacialis, known also with ambiguous common names Arctic cod and polar cod, is an Arctic species of fish in the cod family Gadidae, related to the true cod . Arctogadus glacialis is found in icy water. They grow to about 30 cm long, and are favorite food of narwhals and other arctic whales. The common names "Arctic cod" and "polar cod" can refer to either Arctogadus glacialis or Boreogadus saida, and "Arctic cod" may also refer to Eleginus nawaga.

Source: Wikipedia