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Killer shrimp and demon shrimp are two freshwater shrimp species. Individually they are highly invasive, but now both are found in the UK it's even more concerning for our canals and native wildlife.
Scientific name: Dikerogammarus villosus and Dikerogammarus haemobaphes
Family: Gammaridae
Diet: Aggressive omnivores, both shrimp species eat native invertebrates including fish, fish eggs and larvae, and aquatic insects and larvae.
Size: 3cm
Weight: 80-95mg
Lifespan: 1 year
Native to the area around the Black Sea, both shrimp species have spread over western Europe in the last 20 years, most probably through commercial shipping.
Killer shrimp were first discovered in the UK in 2010, while demon shrimp were found later in 2012.
These crustaceans are considered to be amongst the most damaging invasive species in Europe, with the potential to significantly affect the ecology of our waterways.
Both feast on a range of native species, fish eggs and even young fish, but often kill prey and leave it uneaten. This drastically alters the ecology of habitats they invade and could cause extinctions.
Killer and demon shrimp can tolerate a range of environmental conditions, but they prefer waters with moderate to slow flow speeds, only using faster-moving water to drift to new locations. Their ideal habitats tend to be hard waterway banks, stones or tree roots.
The shrimp and their eggs can survive out of water for up to five days, making them easy to transport on the likes of damp clothing and footwear, and equipment like kayaks and canoes.
This makes it incredibly important to follow the 'Check, Clean, Dry' process each time you exit a canal or river to prevent their spread - even if you're relocating to another spot close by.
At full size, these invasive species are larger than native freshwater shrimp. They both have a striped pattern to their backs, and the tail of a killer shrimp is distinctive with two cone-shaped protrusions.
Killer and demon shrimp are incredibly fast breeders. They can reproduce within 4-8 weeks of birth and at any time of year, as long as water temperature remains above 13 degrees.
Females produce multiple broods of eggs in their lifetime, usually 2-3 times a year. Each brood can contain up to 194 eggs.
Last Edited: 17 April 2025
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