Abstract <p>New information on the distribution of an alien species in the Ural River, the European bitterling (<i>Rhodeus amarus</i>), is provided. Individuals of this fish species have been recorded only in a few localities along a 200-km section of the river between the mouths of the Kolpachka and Alimbet rivers, which is apparently due to its relatively recent introduction. The appearance of the species may be related to its occurrence in pond farms, in which it was accidentally introduced together with fish stocks for farming. An argument in favor of this is the current distribution of the bitterling, which coincided with that of the Stone moroko (<i>Pseudorasbora parva</i>), another recently identified invasive species in the Ural River. The study and analysis of the main diagnostic taxonomic features confirm the naturalization of the European bitterling in the Ural River, and the dynamics of the settlement of representatives of the genus <i>Rhodeus</i> in areas adjacent to the Ural basin was characterized. The phytoplankton in the feeding habitats of the bitterling, mainly microalgae, was also characterized. In total, 90 species were noted in the food spectrum of the species, the most important among which were representatives of the diatom <i>Navicula</i> spp. and <i>Amphora</i> spp. Judging by the selectivity index, the European bitterling prefers mostly representatives of the <i>Amphora</i> spp., <i>Synedra</i> spp., and <i>Cymbella</i> spp. Low values of this indicator are characteristic of taxa of <i>Cryptomonas</i> spp., <i>Oscillatoria</i> spp<i>.</i>, <i>Cosmarium</i> spp., and <i>Closterium</i> spp. The main biomass of algae consumed is made up of benthic and plankto-benthic species. As bivalves of the Unionidae family serve as a spawning substrate for the European bitterling, the wide distribution of these bivalves in the Ural basin has also been characterized, as their occurrence opens up the prospects for further dispersal of this species.</p>