A fairly rapid downstream migration occurs after spawning as sheefish head to their wintering grounds and once again the fish begin feeding. Development of the eggs proceeds slowly in the cold water, with up to six months elapsing before hatching. The fry travel downstream with spring floods to the extensive delta areas of the large rivers. They begin to feed on plankton. Their diet rapidly changes to insect larvae and small fish, and by the second year of life they feed almost entirely on fish.
Adults eat any fish available.
For an arctic freshwater species, the sheefish exhibits a rapid rate of growth. Studies have shown that fish of each stock exhibit distinct growth rates, have a different life span, and reach sexual maturity at different ages. Fish of the Kuskokwim and Minto Flats populations grow the fastest. They reach 16 inches in length at age 2, and up to 30 inches in length and weights to 14 pounds by age 8. Sheefish from the Selawik-Kobuk area grow at a slower rate.