(Dallia pectoralis) the sole representative of the family Dalliidae of the order Esociformes. The body is up to 20 cm long. The blackfish, a freshwater fish, is found in Chukotka, around the islands of the St. Lawrence River, and in Alaska. Blackfish are found in great numbers in small rivers, boggy lakes, and tundra sphagnum bogs. With the onset of cold weather they dig into the silt and hibernate there. Blackfish are characterized by their vitality, and they survive the winter unless their abdominal fluids freeze through. They are not of great commercial significance.
(Globicephalus melas) a mammal of the family Delphinidae, suborder Odontoceti. The fish are up to 6.5 m long and weigh up to 2 tons; the color is black, but some blackfish have gray or white bellies. The jaws are short and equipped with teeth (as many as 40); the forehead protrudes, and the dorsal fin is broad and situated on the front third of the body.
The blackfish is found in seas of the entire earth, except for polar seas. In the USSR on rare occasions it enters the Barents Sea or the seas of the Far East. The blackfish feeds on fish and cephalopod mollusks. Blackfish are hunted only in the North Atlantic, where they are driven onto shore or into narrow bays. They survive well in captivity in aquariums.