Killer shrimp

Dikerogammarus villosus

  • Issued by Inland Fisheries Ireland and the CAISIE project

This species not yet recorded in Ireland.

How do we stop the incursion of this species?

What is it?

A highly predatory and aggressive freshwater invasive species that is rapidly dispersing throughout Europe and beyond. It was recently recorded in individual fisheries in England and Wales.

How do you identify it?

  • Maximum body length is 30 mm (20 mm for native Gammarus species)
  • Like Gammarus species, the body colouration may appear striped or uniform
  • Tail (urosome) with two distinctive cones (see photograph)
  • Large and powerful mandibles
  • Displays particularly aggressive behaviour

Why are we concerned?

Called the killer shrimp because it is a much more deadly predator than native shrimps, mainly due to its larger size and more powerful mouthparts. It preys on a wide range of fish-food insects and small fish, often killing but not eating its prey. It can rapidly replace native insects, thus damaging natural food webs in infested waters. This species can survive for at least six days out of water.