Status LU: present
		Status Eur.: established.
		RA: ISEIA: n/a. Harmonia+: n/a.
Granataugen-Flohkrebs		Wikipedia: / | Wikispecies:/
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Report the species

→ Report Chaetogammarus ischnus to the National Museum of Natural History.

Brief description

Chaetogammarus ischnus (Stebbing, 1899) originates from the Caspian and Black Sea regions. It is a small, slender species with a body length of up to 12 mm. In living specimens, the eyes are bright red, the antennae are orange, and the body is translucent and reddish. The antennae are long and hairy. Its preferred habitats are the lower reaches of larger rivers and streams, canals, and lakes. The species competes with native amphipods for habitat and food. There are no known significant negative impacts on other species groups. Chaetogammarus ischnus occurs sporadically in Germany but is often found in high densities on rock embankments in waterways (e.g., the Rhine and Havel), where it is frequently the dominant species alongside Dikerogammarus villosus. It is a predatory omnivore (feeding on other small animals, insect larvae, and fish eggs) (Müller et al 2018, Kanton Aargau 2026). 

Status and distribution in Luxembourg

Among invasive amphipods, the Pontocaspian species Chaetogammarus ischnus showed an increase in its population between 2018 and 2023, with high prevalence in the Moselle (from Stadtbredimus to Wasserbillig) and the Saar (monitoring by the LfU Rhineland-Palatinate State Office for the Environment).

Risk assessment

ISEIA protocol

no assessed yet

Harmonia+ protocol

no assessed yet

Worldwide distribution

GBIF: https://www.gbif.org/taxon/TC9N#map

Bibliography

• Kanton Aargau, 2026. Neobiota in Gewässern, https://www.ag.ch/de/themen/umwelt-natur/neobiota/neobiota-in-gewaessern?jumpto=Njc1NzcwMC9iZDMxMzc3YS0wMzdjLTQ0NTYtOWEyYS0xODA0MmM0OGNjZjM [Accessed 2026-08-18]
• Müller, R., C. Wolter & T. Peschel, 2018. Neobiota in Berliner Gewässern im Jahr 2018, Wirbellose Tiere, Fische und Wasserpflanzen, Planungsbüro Hydrobiologie Berlin, Im Auftrag der Senatsverwaltung für Umwelt, Verkehr und Klimaschutz, Abteilung Integrativer Umweltschutz, Referat Wasserwirtschaf, pp. 143.