As far as we know, the fishes north and south of Behring’s Straits belong to the same generic or family types as those of the corresponding latitudes of the Eastern Hemisphere, though the majority are specifically distinct. But the information we possess of the fishes of the northernmost extremity of the Pacific is extremely scanty and vague. Farther south, whence now and then a collection reaches Europe, we meet with some European species, as the Herring, Halibut, Hake.
The Chondropterygians are very scarce, and it is doubtful whether another Chondropterygian, beside the pelagic Læmargus or Greenland Shark, crosses the Arctic circle. In the more temperate latitudes of South Greenland, Iceland, and Northern Scandinavia, Acanthias, Centroscyllium, and a species of Raja, also Chimæra, are met with.
Of Acanthopterygians the families of Cottidæ, Cataphracti, Discoboli, and Blenniidæ are well represented, and several of the genera are characteristic of the Arctic fauna: marine species of Cottus; Centridermichthys, Icelus, Triglops; Agonus, Aspidophoroides; Anarrhichas, Centronotus, Stichæus; Cyclopterus and Liparis. Two species of Sebastes are rather common.
Characteristic is also the development of Gadoid fishes, of which some thirteen species, belonging to Gadus, Merluccius, and Molva, form one of the principal articles of food to the inhabitants of the coasts of the Arctic Ocean. The Blennioid Anacanthini or Lycodidæ, are limited to the Arctic and Antarctic coasts. Ammodytes and a few Flat-fishes (Hippoglossoides and Pleuronectes) are common in the more temperate parts.
Labroids only exceptionally penetrate so far towards the north.
Physostomes are very scarce, and represented only by a few species of Clupea and by Mallotus; the latter is an ancient inhabitant of the Greenland coasts, fossil remains, indistinguishable from the species of the present day, being frequently found in nodules of clay of comparatively recent formation.
The Arctic climate is still less favourable to the existence of Lophobranchs, only a few Syngnathus and Nerophis being present in the more southern latitudes, to which they have been carried by oceanic currents from their more congenial home in the south. Scleroderms and Plectognaths are entirely absent.
The Gadoids are accompanied by Myxine, which parasitically thrives in them.