Inconnu (Stenodus leucichthys)

Inconnu (Stenodus leucichthys)

A member of the Salmonidae family and a relative of whitefish and cisco, the inconnu is a species with limited northern range. The only predatory member of the whitefish group in North America, it is highly favored by anglers as an exciting and large sportfish, but it is perhaps the least caught of North American gamefish. Its silvery coloring and tendency to leap high out of the water when hooked have earned it the nickname “Eskimo tarpon.”


The general body shape of the inconnu is very similar to that of a charr or a whitefish, but the head is relatively long, pointed, and depressed on the top. Its mouth is large, and the lower jaw clearly projects outward beyond the upper jaw. The maxillary, or upper jaw bone, extends back at least as far as the middle of the eye.

Small, fine teeth are found on the anterior part of the lower jaw, and on the tongue, the premaxillaries, the head of the maxillaries, the vomer, and the palatines (bones of the roof of the mouth). The tail is distinctly forked. Sheefish have large scales, a dark lateral line, and, like all salmonids, an adipose fin.


Inconnu are said to grow to 60 pounds. The all-tackle world record is a 53-pounder from Alaska. The largest fish may be between 25 and 35 years old.

Life history/Behavior

Spawning takes place in the late summer and the early fall, when inconnu ascend freshwater tributaries. Inland inconnu leave lakes and run up tributaries as well. In coastal regions, inconnu migrate from estuaries to river mouths after ice out, then ascend freshwater tributaries; this migration may last a few weeks in shortlength rivers or months in longer ones. After spawning, they do not die but quickly migrate downstream.

Food and feeding habits

This species feeds mostly on small fish. Salmon smolts, cisco, smelt, and whitefish are among the common forage, and in coastal areas large schools of inconnu will fatten on baitfish prior to their spawning migration.

Other Names

sheefish, connie, Eskimo
tarpon; Russian: beloribitsa.


In North America, inconnu are found in Alaska, from the Kuskokwim River (Bering Sea drainage) north, throughout the Yukon River in Canada, in the Mackenzie River, in Great Bear and Great Slave Lakes in Canada’s Northwest Territories as far as the Anderson River near Cape Bathurst, and in isolated areas of extreme northern British Columbia.

The largest North American fish occur in the vicinity of Selawik to Kotzebue, where tributaries enter into Hotham Inlet and Kotzebue Sound. In Asia, inconnu occur westward as far as the White Sea, and an isolated population inhabits the Caspian Sea and its drainage.


Although generally viewed as a freshwater species, the inconnu occurs in strictly freshwater lakes and rivers and also in anadromous sea-run forms that winter in brackish deltas, bays, and tidewater areas and ascend coastal tributaries to spawn. It evidently evolved from purely freshwater fish to estuarine-anadromous fish.