Any one of numerous species of small fish of the family Gasterosteidae. The back is armed with two or more sharp spines. They inhabit both salt and brackish water, and construct nests from weeds.

plural of stickleback

Gasterosteus aculeatus, an endangered species of European stickleback.

plural of threespine stickleback

Gasterosteus aculeatus, a small fish of coastal and inland waters of the Northern Hemisphere, that can make its spines erect when threatened, which makes it hard to swallow.

Gasterosteus aculeatus, a small fish of coastal and inland waters of the Northern Hemisphere, that can make its spines erect when threatened, which makes it hard to swallow.