Freshwater Shrimp - Gammarus pulex/fossarum agg.

Alternative names
River Shrimp

A greyish or brownish freshwater crustacean growing to 21 mm but usually much less . Not a true shrimp, but sometimes referred to as the Freshwater Shrimp or River Shrimp.

Identification difficulty

Freshwater. They prefer flowing water but have also been found in ponds.

When to see it

All year round.

Life History

The life cycle of Gammarus pulex is complex. Males grab and hold females before deciding which one is likely to produce lots of eggs. Then the male carries his chosen female for several weeks until she sheds her skin and the male can mate with her. He then lets her go and she carries the developing young in a brooding pouch. After about a month, the young shrimps swim out of the brood pouch, and a few months later they can breed themselves. As females can produce up to 50 young each month, the population soon grows.

UK Status

Common and widespread in Britain.

VC55 Status

Common in Leicestershire and Rutland.

be our species champion

Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map