10 20 40 60 cm
mittakaava < 20 cm
Gösta Sundman: Suomen Kalat (Kansalliskirjasto, The National Library of Finland), Lauri Urho
- Other names: Sea stickleback
- Family: Sticklebacks and tubesnouts – Gasterosteidae
- Similar species: None in Finland
- Size: 8–15 cm.
- Appearance: With its curious shape, the 15-spined stickleback differs greatly from Finland’s other sticklebacks. It looks like a cross between a pipefish and a pike – if such were possible! The fan-like caudal fin is typical of the sticklebacks, as is the slim caudal peduncle, though this is unusually long – over one-third of the fish’s body length. As in other members of the family, the first dorsal fin consists solely of spines. They are small and 14-15 in number. Typically too, the pelvic fins are merely spines. The second dorsal fin and anal fin are similar in size and located just anterior to the long caudal peduncle. Mouth at end of long snout.
- Colouring: Back brownish yellow, sides with darker indistinct markings. Belly white and silvery.
- Reproduction: Spawns in May-June among bladderwrack, the male building a nest 5-8 cm across from bits of vegetation. The male guards and fans the eggs and remains with the fry after hatching until they have used up the contents of their egg sacs and can fend for themselves. Adults are thought to die after spawning.
- Food: Plankton and fish fry.
- Distribution and habitat: The 15-spined stickleback is a fish of the sea and is unable to live in fresh water like Finland’s other sticklebacks. It requires a salt content of at least 0.5%, which restricts it to the area between Kotka in the east and Kaskinen on the Gulf of Bothnia. Most common in the SW archipelago and around the Åland islands. It spends most of its short life, which is little more than a year, concealed in bladderwrack or eel grass. Presumably spends the winter in slightly deeper water. 15-spined sticklebacks are solitary fish, lurking among vegetation ready to ambush any food items that approach too close. May dash out to snatch its prey rather like a pike.