Institute of Zoology, Azerbaijan National Academy of Sciences
The article presents the number of species by groups registered by individual researchers in inland waters of the country (springs, rivers, reservoirs, lakes, etc.). Detailed information on the most common and dominant species in our water resources, their role in the ecosystem, etc. are provided. Since the beginning of scientific and zoological research, more than 1000 species of protozoan animals (mainly ciliated infusoria), more than 1350 species of invertebrate animals (mainly rotatory (more than 300 species) and insect larvae (more than 586 species)), 190 species of vertebrates [mainly birds (97 species) and fish (67 + 1 species) and 332 species of fish parasites (mainly myxosea (59 species), flatworms (69 species) and trematodes (81 species)] have been revealed. Indicating the species number of hydrobionts, will be changed as a result of future studies, since some groups of hydrabionts still remain unexplored, or only 1-2 species were accidentally recorded in the study. In addition to unicellular animals, cervical worms, nematodes, crustaceans, tusks, and other insect larvae can be included.