The Black, Azov and Caspian Seas are donor hotspots for non-native species, with many species from the region highly tolerant of abiotic stressors and able to successfully establish, spread and exert impacts around the world. Here we document a new introduction of the bloody red mysid shrimp, Hemimysis anomala G.O. Sars, 1907. Discovered for the first time in January 2023 in Lake Stechlin, Germany, at high densities, many questions surround its potential impacts in this deep, formerly oligotrophic, now meso-eutrophic lake of major geological, cultural and ecological importance. Using molecular and morphological identification, the identity of H. anomala from two sites in the lake was confirmed. Unlike other mysids normally detected over deeper waters in lakes at night, H. anomala has so far only been detected near the surface and at depths shallower than 30 m, but during both night and day, in winter. We outline vital areas for future research and the need for dedicated sampling methods by also highlighting a case study from Lake Müggelsee, Berlin, where the species has been known to exist for over 20 years without being caught in regular plankton tows.
