Palaemon varians

Palaemon varians, known as the Atlantic ditch shrimp^[2] and variable shrimp,^[3] is a caridean shrimp^[1][3] found from the Baltic Sea and the British Isles to the western Mediterranean Sea.^[4] It reaches up to 5 cm (2.0 in) in length and is never found in fully marine conditions, instead living in brackish water.^[4]

Palaemon varians
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Caridea
Family:	Palaemonidae
Genus:	Palaemon
Species:	P. varians
Binomial name
Palaemon varians Leach, 1814
Synonyms[1]
Palaemon variabilis Bouchard-Chanteraux, 1829 Palaemonetes varians (Leach, 1814)

In the aquarium

Palaemon varians in a temperate freshwater aquarium

Sold by aquarium retailers as grass shrimp, they have a high tolerance of varying salinity^[5] and temperature levels ranging from 1 °C to 30 °C for prolonged periods of time.^[3] They will feed on any leftover fish food, algae or plant life and are generally peaceful by nature when mixed with similar sized aquarium life.