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Killer Shrimp, Freshwater Shrimp and Bloody Red Shrimp

Aquatic Invasive Species: Identification Booklet of Freshwater Invasive Species in Quebec

Aquatic Invasive Species: Identification Booklet of Freshwater Invasive Species in Quebec (PDF 4.6 MB)

Table of contents:

Aquatic invasive species in Quebec

Killer Shrimp

(Dikerogammarus villosus)

Killer ShrimpPhoto credit: S. Giesen

Freshwater shrimp (scud)

(Echinogammarus ischnus)

Freshwater Shrimp Photo credit: Colin van Overdijk 

The Killer Shrimp and Echinogammarus ischnus (Freshwater Shrimp) are 2 small invasive scuds (gammarids). They have the appearance of curved shrimps with laterally compressed bodies.


Killer Shrimp Freshwater Shrimp
  • up to 3 cm
  • two pairs of antennae
  • fan-shaped tail
  • curved and semi-transparent body, uniform colour or striped
  • average of 1 cm
  • v-shaped tail
  • curved, semitransparent bod

Killer ShrimpPhoto credit: Michal Grabowski

Freshwater ShrimpPhoto credit: Colin van Overdjik


These 2 species are native to the seas located in the centre of Europe and Asia. The Killer Shrimp has not yet been recorded in North America. However, E. ischnus was first observed in the Detroit River in 1994. It was introduced through ballast waters from ocean-going vessels. Through watersports and recreational fishing, it has since spread to the Great Lakes and the Upper of the St. Lawrence River. It was found near Gentilly in 2010.


The Killer Shrimp and E. ischnus are species found in lakes and rivers, where the current is weak or moderate. They are able to live in both fresh and brackish waters because they can tolerate large variations in temperature and salinity. They usually colonize rocky, gravelly or shell-strewn bottoms that provide shelter. E. ischnus can be found on bottoms with sand and clay, near solid surfaces like docks and submerged structures.

Similar species

The Killer Shrimp and E. ischnus resemble several native gammarids such as Gammarus fasciatus. It is very difficult to tell them apart without a microscope and, usually, only experts can do it.

Gammarus fasciatus

Gammarus fasciatus
Photo credit: Yale Peabody Museum of Natural History, Eric A. Lazo-Wasem

Bloody Red Shrimp

(Hemimysis anomala)

Bloody Red Shrimp Photo credit: S. Pothoven Great Lakes Environmental Research Laboratory


Bloody Red Shrimp
 Photo credit: DFO

Bloody Red ShrimpPhoto credit: National Oceanic and Atmospheric Administration


The Bloody Red Shrimp is a small crustacean native to the coastal regions of the seas of central Europe. It was first intentionally dispersed in Europe between the late 1940s and the 1980s to increase fish productivity. Its dispersion continued via ballast waters of ocean-going vessels. It then ended up in the Great Lakes, except Lake Superior, as well as the St. Lawrence River since 2008.


Although it can tolerate brackish waters, the Bloody Red Shrimp lives mostly in fresh waters with weak or moderate currents. It is often found near docks, ships, and maritime structures, finding refuge in bottoms strewn with rocks and shells. It moves in swarms and can shift very quickly when disturbed. During the day, the Bloody Red Shrimp migrates in deep water to avoid light and rises to the surface at night to feed on insect larvae and plankton.

Similar species

The Bloody Red Shrimp resembles a native shrimp found in the Great Lakes, the Opossum Shrimp (Mysis diluviana). However, the tail of the Opossum Shrimp is forked. Using a magnifying glass helps to see this difference.

Opossum Shrimp

Opossum Shrimp
Photo credit: National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory
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