Blackspotted Stickleback (Gasterosteus wheatlandi) - Native

A 1.8-inch blackspotted stickleback. Robert J. Eakins photo.

Identification. Very similar to threespine stickleback. Dorsal spines 3. Pelvic fins with 1 sharp spine and 2 soft rays. Well-developed cusp (pointed projection) at base of pelvic fin spine. Pelvic bones joined across breast. No lateral keel on caudal peduncle. 5-6 bony plates on sides. Color typically light silver. Black spots along sides may be faint. During spawning the body becomes yellowish-green and the black spots become more conspicuous.

Size. Commonly 1 to 2 inches. State survey max. size 3 inches. Max. reported size 3 inches.

Distribution. East Coast from Newfoundland to Long Island. In Connecticut, they occasionally enter the mouths of most freshwater streams that enter Long Island Sound, where they are probably uncommon to rare in abundance.

All maps created in 2009. See CT DEEP Fish Community Data for updated distributions.

Habits. Prefer vegetated areas of coastal marine waters, estuaries, and tidal creeks. They enter brackish water in the late spring to spawn. Rarely enter entirely fresh water. Can be captured with small-mesh dip net or seine.

Comments. The blackspotted and threespine sticklebacks are so closely related that taxonomists have debated whether they should be designated as separate species. Rarity and difficulty with identification cause the blackspotted stickleback’s whereabouts in Connecticut to be unclear.

Text and images adapted from Jacobs, R. P., O'Donnell, E. B., and Connecticut DEEP. (2009). A Pictorial Guide to Freshwater Fishes of Connecticut. Hartford, CT. Available for purchase at the DEEP Store.