This fish is eel-like in form and resembles the ocean pout in most other respects as well, except that it is more slender (about 14 to 16 times as long as it is deep), and that there is no separation, apparent or real, between its dorsal, caudal, and anal fins, but the three form a single continuous vertical fin running along the back, around the tail, and forward on the lower surface to the vent. The dorsal fin not only originates [page 516] farther back than in the ocean pout (over the tip of the pectoral instead of in front of the base of the latter), but all the dorsal rays (about 92) are soft. Furthermore the anal fin (about 88 rays) extends relatively farther forward than in the ocean pout. The pectoral fins are rounded like those of the ocean pout, but smaller relatively, the small ventrals are similarly located well forward of the pectorals, and in small specimens the head resembles that of its relative in profile except for a somewhat wider mouth. Old males, however (fig. 271), "are transformed almost beyond specific recognition by an extraordinary development of the entire head in advance of the eyes. The snout becomes shovel-shaped, its length equal to two-fifths that of the head, while in the normal condition it is one-fourth".
The sides are light brown above the lateral line, white below it, with a series of 8 to 10 irregular dark brown patches which the lateral line bisects. The belly is blue, its lining jet black.
Maximum length about 10 inches; usual length about 4 to 6 inches.
This is a bottom fish, living on mud or sand and confined to considerable depths of water. Normally, 25 to 30 fathoms is its upper limit, but the fact that the Grampus specimen mentioned below was taken in a tow net, though close to bottom, proves that it sometimes rises from the ground. To the southward, on the continental slope, it has been trawled down to 603 fathoms.
Nothing is known of its way of life or of its breeding habits.
So far known only off the coasts of Nova Scotia and of New England, and southward along the continental slope to the offing of Beaufort, N. C., in rather deep water.
The wolf eel has been trawled at many localities on the continental slope at 200 to 600 fathoms from the offing of Cape Fear, North Carolina (lat. 34°40' N., long. 75°15' W.) to abreast the western end of Georges Bank (long. 68°22' W.). It was formerly regarded as very rare within the Gulf of Maine, the only records for it there up to 1925 having been of a few specimens trawled off the mouth of Passamaquoddy Bay in 35 to 50 fathoms; of one 4 inches long taken off Monhegan Island by the Grampus on August 2, 1912, in 60 fathoms; and of several that were collected by the U. S. Fish Commission many years ago off Cape Ann in 75 to 110 fathoms, in the Western Basin in 115 fathoms, and off Cape Cod. More recent captures, however, of a number of wolf eels at about 90 fathoms in the trough west of Jeffreys Ledge by the Albatross II in November 1927, in August 1928, and in September 1930 (a total of 61 specimens) show that they are more plentiful in the deeper parts of the Gulf than the previous record might have suggested.
The only definite records for the wolf eel eastward from Cape Sable are of 5 specimens taken by the U. S. Fish Commission steamer Speedwell 3 miles off Cape Negro, Nova Scotia, in 90 fathoms, in the summer of 1877, and of one taken 27 miles off the entrance to Halifax Harbor (Chebucto Head) in 101 fathoms.
 Goode and Bean. Smithsonian Contrib. Knowl., vol. 30, 1895, p. 310.
 Goode and Bean (Smithsonian Contrib. Knowl., vol. 30, 1895, p. 310) give a long list of localities from the early cruises of the U. S. Coast Survey and of the U.S. Fish Commission. And Beebe (Zoologica, N. Y. Zool. Soc., vol. 12, 1929, p. 18) has reported a wolf eel from the Hudson Gorge, off New York, at 69 fathoms.
 Reported by Goode and Bean, American Jour. Science, ser. 3, vol. 14, 1877, p. 473.
 Probably these specimens were the basis for Jones' (List Fishes Nova Scotia, 1879, p. 5; Proc. Nova Sootian Inst. Sci., vol. 5, 1882, p. 91) statement that the wolf eel occurs on the Nova Scotian fishing banks.