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northern studfish

northern studfish (Fundulus catenatus) Photo © Uland Thomas

Features and Behaviors


The northern studfish may grow to six inches in length. Its life span is about five years. The northern studfish has silvery sides with many horizontal stripes. The back is yellow-brown with a short, gold stripe in front of the dorsal fin. The dorsal and tail fins have small brown specks. The breeding male is bright blue with red-brown streaks and red spots on the head and fins. Its paired fins are yellow, and the tail fin has an orange fringe with a black band.


The northern studfish lives in streams with permanent flow, clear water and a bottom of sand, gravel or rock. This fish moves in small groups in very shallow water. Spawning occurs from mid-May to August. The male establishes and guards a territory. Eggs are deposited on gravel. This fish eats insects, snails, clams, crayfish and earthworms.

Illinois Range


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Fundulidae

Illinois Status: common, native