Aim. Description of the results of molecular genetic studies of a number of fish, narrow-clawed crayfish, and mollusk species. Methods. For the analysis, RAPD, SSR, and DNA-barcoding methods were used. Results. Unique RAPD amplicones were identified to differentiate Lahvinsky, Tremlyansky and Isobelinsky carp breeds. With the use of SSR markers, the Dniester-Dnieper and Kama population belonging to the sterlet, grown in two farms of Belarus, was established. An instruction on the application of molecular genetic analysis to establish the species belonging to meat and caviar of sturgeon species was developed. The species composition and genetic polymorphism in narrow-clawed crayfish in reservoirs of Brest and Gomel regions was estimated. The work on DNA-barcoding of mollusks has begun. Conclusions. Molecular-genetic passports of carp breeds of Belarusian breeding are compiled. The population belonging to sterlet is determined in two fish farms inBelarus. Instruction for the use of molecular genetic analysis to establish the species (population) belonging to the sturgeon fish and their products is introduced in the country and used for testing and certification of sturgeon products. For the Byelorussian Polesie region, it is established that the narrow-clawed crayfish in theGomel region reservoirs has the greatest genetic diversity. Keywords: molecular markers, carp, sturgeon, narrow-clawed crayfish, mollusks.