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Threespine stickleback (Gasterosteus aculeatus)

Threespine stickleback Common Names: Twospine stickleback, banstickle, spanstickle, saw-finned stickleback, eastern stickleback, tittlebat.

Description: In early 1980s it spread to Lake Michigan, most likely from ballast water, canals and bait bucket transfers; now established in other Great Lakes. Spread by range expansion via canals and diversions; ballast water.

Identification: Up to 4 inches; silver with dark mottling; 3 stout dorsal spines (first two are longer than the third); large eyes; body scaleless with bony plates; breeding fish are colorful and defend their nests aggressively; nests on aquatic vegetation.

Habitat: Native to both coasts of the United States. Found in both salt water and fresh water; shores of larger lakes; shallow, sandy weedy areas in rivers, streams and ponds.

Reproduction: Defends their nests aggressively and nests on aquatic vegetation.

Impact and Damage: Aggressive invader that preys on native species and competes for food and habitat. Will eat eggs and larvae of native fish, capable of hybridizing with native sticklebacks and their stout spines discourage predators.

Monitoring and rapid response: Clean, drain, dry.

Credits: The information provided in this factsheet was gathered from "Invaders of the Great Lakes" produced by Wildlife Forever, the Sea Grant Great Lakes Network and the Ohio DNR.

Individual species images that appear with a number in a black box are courtesy of the network ( Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (

Common Name:

Threespine stickleback

Scientific Name:

Gasterosteus aculeatus