Brown Bullhead Ameiurus nebulosus (Siluriformes: Ictaluridae)—A New Species in the Neman River Basin

The article provides data on the first record of the brown bullhead Ameiurus nebulosus in the Neman River basin. Statistically significant differences in the morphometric characteristics of the brown bullhead specimens from the Neman River basin compared to the specimens of the Western Bug basin (place of initial introduction in Belarus) according to 11 morphometric characteristics were shown. A wider range of variations in the number of rays in the fins of fish from Belarus compared to the native range was noted. Data on the level of genetic polymorphism for the mitochondrial COI gene in populations of brown bullhead from water bodies of the acquired range (including the Neman River basin) compared to natural range were presented.