[4] The color of G. roeselii individuals can vary from green to brown, gray, or yellow, and some have reddish markings on parts of their carapaces.

The distinctive spines of G. roeselii were found in a laboratory experiment to be associated with defense against predation by brown trout.

[17] Gammarus roeselii are a successful invasive species due to their high reproductive rate, tolerance to changing environmental conditions and unique anti-predation characteristics.

[citation needed] G. roeselii's mechanism of invasion is still unknown but it is most likely due to human activities such as aquaculture or fish repopulation.

[citation needed] G. roeselii were once used as a food source in commercial fisheries, so it is possible that some individuals escaped and were able to populate new areas.

[citation needed] G. roeselii have the ability to easily attach their bodies to substrates by using the spines on its metasomes.

[citation needed] These organisms are also able to survive out of water for several days at a time, making the transfer of G. roeselii feasible over land.

In the 1980s, the insecticides Dyfonate and Ditrifon (which has since been banned in the European Union, India, and other countries) were found to be toxic to G.