blackfish

noun, plural (especially collectively) black·fish, (especially referring to two or more kinds or species) black·fish·es.

1. any of various dark-colored fishes, as the tautog, Tautoga onitis, or the sea bass, Centropristes striatus.
2. a small, freshwater food fish, Dallia pectoralis, found in Alaska and Siberia, noted for its ability to survive frozen in ice.
3. black whale.

noun plural -fish or -fishes

1. a minnow-like Alaskan freshwater fish, Dallia pectoralis, related to the pikes and thought to be able to survive prolonged freezing
2. a female salmon that has recently spawnedCompare redfish (def. 1)
3. any of various other dark fishes, esp the luderick, a common edible Australian estuary fish
4. another name for pilot whale