Pygmy Whitefish

Prosopium coulterii

The pygmy whitefish (Prosopium coulterii) is a small freshwater fish in the family Salmonidae. Adults typically reach only 10-15 cm, making them one of the smallest salmonids. They have a slender, silvery body with an olive-brown back and a small adipose fin. This species inhabits deep, cold lakes and occasionally streams at depths of 10-100 meters across northwestern North America, from Alaska and British Columbia to Montana and the Great Lakes region. Pygmy whitefish are glacial relicts, persisting in cold, deep lake habitats since the last ice age. They feed primarily on small crustaceans, insect larvae, and zooplankton near the lake bottom. Due to their small size and deep-water habits, they are rarely encountered by divers but are ecologically significant as indicators of pristine glacial-origin water bodies and as prey for larger predatory fish including lake trout and bull trout.