Among other groups of hydrobionts, free-living ciliates are the primary consumers of aquatic ecosystems and they play an important role in the processing of organic matter. This group of free living protozoa is actively involved in the production and destruction of organic matter at primary trophic levels. Under favorable environmental conditi\ons, free living ciliates have the ability to multiply intensively and form a high biomass. Studies by a num¬ber of authors have shown that due to their abundance of free-living protozoa, their biomass is several grams per liter of water and this, in turn, is comparable with the biomass of multicellular animals living in aquatic biotopes