The Pygmy Whitefish escaped detection in Lake Superior until 1952 when deep water trawls conducted by the U.S. Fish and Wildlife Service discovered this disjunct population over 1000 miles east of the species known range which extends from the headwaters of the Columbia River in Montana and Washington northward into Alaska. Because of this great distance between these ranges, the Lake Superior population is believed to be a glacial relict. The Pygmy has a brown back, silver sides, and a white belly. Juveniles have 8-11 round parr marks along the lateral line. In Lake Superior, the Pygmy's maximum recorded length is 5.4 inches.
Females have deeper and broader bodies and males have longer rayed fins.
Spawning is believed to occur in November or December. The Pygmy Whitefish has been found at depths of 59 to 297 feet, but is most abundant at 152 to 234 feet. Their diets consist mostly of crustaceans called Pontoporeia. The Pygmy's most common associates are the Ninespine Stickleback, and Deepwater, Slimy, and Spoonhead Sculpins. The Spoonhead Sculpin is found in all the Great Lakes and most of Canada including the brackish waters of James Bay.