Spinachia is a monospecific genus of ray-finned fish belonging to the family Gasterosteidae, the sticklebacks.

The anterior dorsal fin consists of a series of fourteen to fifteen small, widely separated spines.

[3] The fifteen-spined stickleback is native to coastal waters in the northeastern Atlantic Ocean where it lives among bladderwrack and eel grass.

Breeding takes place in May and June among bladderwrack, with males building nests out of bits of seaweed, and guarding and fanning the eggs with his fins until they hatch.

The males continue to care for the fry until they have absorbed the contents of their egg yolks and can feed for themselves.