The article presents the results of an experiment to assess the effect of feed additive of humates on the growth rate and survival of different age groups of sterlet (Acipenser ruthenus L., 1758) and the conversion of fish feed for keeping in aquaculture. Based on the analysis of sources of scientific and technical information, it was found that humic drugs have long been used in crop production as growth stimulants and microfertilizers, and in animal husbandry - to normalize metabolism, treatment of digestive diseases and general stimulating effect on the body as a whole. Analysis of data on the use of humates in aquaculture indicated the presence of a positive effect of these compounds on individual cultivation objects. The small amount of information on the use of humates in fish farming has led to the conclusion that this direction of fish farming intensification is still insufficiently studied, and that studies of the impact of humic substances on aquaculture objects are not comprehensive and mainly concern the assessment of individual effects of biologically active action of the compounds on fish. The available information gave grounds to speculate about the prospects for the use of humates in sturgeon farming. To test this assumption, a series of experiments was conducted on the feeding of sterlet feed with the addition of sodium humate. The research was conducted in 2018, 2020 and 2021, in the production conditions of the cage fishery, located on the Kaniv Reservoir. The effect of different concentrations of sodium humate feed additives on one- and two year old sterlet was evaluated. It was found that the addition of sodium humate to fish feed in concentrations of 60, 100, 120 and 200 mg / kg of feed did not significantly affect the growth rate of sterlet. Thus, the advantage of experimental variants over the control for this indicator was insignificant, in the range of 1.0-1.6%. The effect of sodium humate on the survival of this year sterlet, for their cultivation in gardens. At the same time, the best, by 6.7-17.4%, feed conversion with the addition of humates by one- and two-year-old sterlet was noted. According to the results of the experiments, the best result was obtained in the variant using a feed additive of humates at a concentration of 200 mg / kg of feed. It is considered promising to continue the study of the impact of feed additives of humates on the growth and survival of valuable aquaculture objects under different housing conditions, in particular in closed recirculation aquasystems (RAS), as well as finding the optimal concentration of these additives in feed for different species and age groups of fish.

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It was conducted comprehensive ichthyological and ichthyopatological research of European perch (Perca fluviatilis L.) populations in lakes of Shatsk National Nature Park and the impact of Triaenophorus nodulosus invasion on its size, weight and reproductive ability. Morphometric analysis, absolute and relative fecundity of fish were determined by the methods generally accepted in ichthyology. Clinical examination of fish (2,225 specimens, including European perch -1650 specimens) was performed during control catches. Simultaneously, the weight, size, and age of the fish were determined. Morphometric analysis was performed on 120 specimens of perch with the length of 104.4-194.8 mm and the weight of 16.4-177.6 g. Pathoanatomic autopsy of the fish was performed in the field and laboratory conditions. Parasitological studies were performed by the method of incomplete parasitological analysis. The extent and intensity of the invasion were determined. When conducting research on the parasitofauna of native fish species in the lakes of the Shatsk National Nature Park, it was found their infestation with helminths of various systematic positions (Triaenophorus nodulosus, Khawia sinensis, Raphidascaris. acus, and Philometroides lusiana). Perch was the most infected with the helminths. The invasion caused by the plerocercoid of Cestoda T. Nodulosus was the most intensive (18.2-56.3%, depending on the reservoir). There was a significant difference in the measurements of non-infested and infested with T. nodulosus fish individuals of the same age, we also registered significant lag in growth and a decrease in body weight among the infested specimens. A steady trend towards a decrease in fecundity parameters was also observed in infested fish. Thus, in non-infested individuals of 4-year perch, the highest individual absolute fecundity (IAF) was 6.7 thousand eggs against 3.1 thousand eggs in the infested perch (Lucimer lake). The lowest IAF – 3.9 thousand eggs against 2.0 thousand eggs in the infested perch specimesn was found in Chorne Velyke lake. In non-infested individuals of 5-year perch, the highest IAF index was 9.4 thousand eggs when compared to 6.8 thousand in the infested perch (Pulemetske lake). The lowest IAF was 6.3 thousand eggs (Chorne Velyke lake). The highest IAF was recorded in perch from Pulemetske lake (34.6 thousand eggs in non-infested versus 10.3 thousand eggs in infested specimens). The lowest IAF was observed in perch from Chorne Velyke lake (9.1 and 6.6 thousand eggs, respectively). There was decrease in fish size, weight and fecundity in perch infested with Tr. nodulosus, but it did not affect the reproductive fish ability.