Brook Stickleback

Characteristics

A deep-bodied, compressed and scaleless fish. The mouth is small with swollen lips, and the lower jaw projects beyond the upper jaw. There are two to seven (usually five) unconnected spines followed by a dorsal fin with 9 to 11 rays. The anal fin has a single spine with 9 to 10 rays; the pelvic fin has one heavy spine with a single ray. The lateral line is complete, and there are 30 to 36 small, bony plates along its full length. It is olive-green on the back and sides with white or yellow spots and dark wavy lines scattered over the sides. This species reaches 2- to 3-inches long.

Distribution

Streams and some natural lakes throughout central and northeast Iowa, with scattered populations found in the Little Sioux River and Rock River drainages in northwest Iowa. It appears to be present only in the northern one-half of the state.

Foods

Aquatic insects

State Record

State Records are not documented for non-game species.

Expert Tip

Brook Stickleback make interesting aquarium fish, but because of their aggressive behavior, it is difficult to keep other small fish with them.

Details

In Iowa and other parts of the upper Midwest, the Brook Stickleback prefers streams with moderate currents that have sand and gravel bottoms and clean to slightly turbid water. It can also be found in the sheltered bays, swampy margins and bogs of lakes. It lives in cool, shallow water, often with heavy vegetation. 

Males build nests in the spring at water temperatures of 59 to 66 degrees. The nests are attached to a stem of vegetation by a whitish cement secreted by the male. A rounded nest is built from organic debris, filamentous algae and other materials. The male aggressively seeks a female that is pregnant. The female enters the nest opening and is continuously prodded by the male until eggs are deposited. Immediately after leaving the nest the female is chased away by the male. The male then enters the nest and fertilizes the eggs. The eggs are incubated by the male, vigorously fanning a current of water through the nest. Eggs hatch in 7 to 11 days, depending upon water temperature.

The male Brook Stickleback continues to guard the nest after the eggs hatch, retrieving fry that stray from the nest by catching them in his mouth one at a time and spitting them back into the nest. After several days, young escape so fast that the male is unable to retrieve them; he either abandons his duties as a father or eats his own offspring. Brook Stickleback live up to three years.

The Brook Stickleback is food for numerous game fish.

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.

Illustration by Maynard Reece, from Iowa Fish and Fishing.