Stickleback
A family of small ray-finned fishes with dorsal spines found across the Northern Hemisphere.
Sticklebacks belong to the family Gasterosteidae and inhabit temperate waters worldwide. They are well known for their distinct dorsal spines and have become key models in evolutionary biology research.
- Sticklebacks lack scales but feature prominent dorsal spines.
- Males build nests and guard eggs for up to two weeks.
- Freshwater males develop bright red throat coloration.
- They are key models for studying parallel evolution.
- Saved thousands during the Leningrad Siege via consumption.
What it is
Sticklebacks form a group of ray-finned fishes within the family Gasterosteidae. These creatures live in temperate regions across the Northern Hemisphere, occupying freshwater streams, brackish estuaries and coastal seas. They lack typical scales, though some possess bony armour plates along their sides. A defining physical trait is the presence of strong, isolated spines in their dorsal fins. Most individuals are small, typically measuring around three inches, with the fifteen-spined variety reaching up to twenty-two centimetres. Their body shape adapts to their environment, becoming deeper in shallow waters or slimmer in deep lakes.
Where it lives
The family displays a Holarctic distribution, meaning they are native to temperate zones in both North America and Eurasia. While primarily marine, many populations inhabit freshwater systems. After the last Ice Age, roughly ten thousand to twenty thousand years ago, ancestral groups became isolated in European, Asian and North American water bodies. This separation allowed freshwater lineages to evolve distinct features compared to their ocean-dwelling relatives. They thrive in diverse aquatic settings, from shallow littoral zones to deeper oligotrophic lakes where food sources differ significantly.
How it lives
These fish are carnivores that consume small animals like insect larvae, crustaceans and young fish. Research indicates they exhibit distinct personality traits, ranging from bold to shy behaviours that influence leadership roles within groups. In shallow lakes, they often develop deeper bodies to hunt benthic invertebrates, whereas those in deeper waters adopt slimmer forms for plankton feeding. Predators include larger fish and birds. Their social structure varies, with some species shoaling while others display solitary tendencies during specific life stages.
Breeding and life cycle
All species share unique mating rituals. Freshwater males develop bright red throats and construct nests using weed held together by a kidney secretion called spiggin. Males perform a zig-zag dance to attract females, who signal readiness with a head-up posture and distended bellies. The female deposits eggs into the nest, where the male fertilises them. He then guards the clutch for seven to fourteen days until hatching, continuing protection of the fry afterwards. This high parental investment limits the number of mates per season but allows for multiple spawning events.
Fish and people
Sticklebacks hold significant value in scientific research rather than commercial use. Niko Tinbergen used them to establish ethology as a discipline through studies on fixed action patterns. Today, they serve as supermodels for studying molecular genetics and evolutionary change in wild populations. Their genome reveals how parallel evolution occurs between marine and freshwater environments. Culturally, a sculpture in Kronstadt honours the fish for helping save residents from starvation during the Leningrad Siege of World War II.
Questions people ask about Stickleback
What do sticklebacks eat?
They are carnivorous predators that feed on small aquatic animals. Their diet consists mainly of insects, crustaceans and fish larvae found in their freshwater or marine habitats.
Why are sticklebacks important to science?
They are considered supermodels for evolutionary biology. Researchers study their genomes to understand how species adapt to different environments, particularly the transition from saltwater to freshwater ecosystems.
How do male sticklebacks attract females?
Males build nests from weeds using a special secretion. They perform a zig-zag dance and display bright red throats to signal fitness. Females choose mates based on this colouration and nest quality.
Are all sticklebacks the same size?
No. Most species stay around three inches long. However, the fifteen-spined stickleback is much larger, reaching approximately twenty-two centimetres in length.
Good reading and sources
The facts on this page come from the Wikipedia article "Stickleback", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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