Threespine Stickleback

Author: Anil Mishra 

Photos: Anil Mishra and D. Young

Common Names:  Threespine Stickleback, Three-Spined Stickleback, Common Stickleback

Scientific Name: Gasterosteus aculeatus

Size range: 5-10 cm (to 4in)

Habitat:  The Threespine Stickleback can be commonly found in British Columbia but they have also been found in the Bering Sea, Northern California, and parts of East Asia. They can tolerate many water conditions and may live in fresh water lakes, ponds and ditches, brackish water, as well as in the ocean.  They are often found in schools in shallow water along docks in the Pacific Northwest. 

Food (Prey):  The main diet of the Threespine Stickleback in fresh water are water fleas, mayfly larvae, and sometimes smaller fish.  In the ocean they eat a variety of small plankton and invertebrates such as copepods.

Identifying Features:  The Threespined Stickleback has 3 pointed spines at the top, bony plates on the side that act as armour, and a spine in the pelvic fin. It is usually coloured silver, green, blue or  black but in freshwater they are usually brown.  During breeding the males’ throat region becomes bright red and the eyes a striking blue. 

Illustration by D. Young

Predators:  Bigger fish will try to catch the Threespine Stickleback but the Stickleback’s armour can protect them.  The Threespine Stickleback is also pretty aggressive and will fight off predators which can result in some bigger fish avoiding them.

Behaviour:  The Threespine Stickleback are actually pretty social and will sometimes join groups of fish that look similar to them.  They are often studied for their behaviour during courtship, mating and when protecting their territory. 

References

Gotshall, D. (2001). Pacific Coast inshore fishes. Sea Challengers, Incorporated.

Lamb, A., & Edgell, P. (2010). Coastal Fishes of the Pacific Northwest Revised and Expanded Second Edition. Harbour Pub.

Lamb, A., Lamb, A., & Edgell, P. (1986). Coastal Fishes of the Pacific Northwest. Harbour Publishing.

Threespine stickleback. (n.d.). Wisconsin Sea Grant. Retrieved January 24, 2024, from https://www.seagrant.wisc.edu/our-work/focus-areas/ais/invasive-species/invasive-species-fact-sheets/fish/threespine-stickleback/ 

Wood, S. (2020). ADW: Gasterosteus aculeatus: INFORMATION. Animal Diversity Web. Retrieved January 15, 2024, from https://animaldiversity.org/accounts/Gasterosteus_aculeatus/Â