Purpose. Development of a method for the regeneration of highly porous fillers for biofilters after slagging of their pores with biofilm residues in the process of growing aquaculture objects in recirculating aquaculture systems (RAS). Methodology. Regeneration of fillers was performed with solutions of sodium hypochlorite of different concentrations (2.5%, 1%, 0.5% of active chlorine) after their exploitation for 6 months. The cleaning efficiency was monitored by the difference in fillers weights after cleaning. Findings. According to the study, the use of sodium hypochlorite for cleaning highly porous fillers for biofilters (using an example of porous ceramic filler and foamed glass «JBL Micromec») is efficient and cost-effective. A reduction in the weight of the test samples averaged 12.95% for porous ceramics and 15.01% for foamed glass. Based on the obtained data, aqueous solutions with different concentrations of sodium hypochlorite do not have a pronounced difference in efficiency, respectively; the optimal for use is a 0.5% solution. Originality. The use of highly porous fillers for biofilters has long been unprofitable in fish farming due to the rapid loss of their main advantages - a high specific area per unit volume as a result of micropore slagging with biofilm residues. As a result, complete regeneration of these filter materials was required annually, which, given the significantly higher cost compared to polymeric fillers, made their use unprofitable. The described technique allows the use of porous ceramics and foamed glass, after their restoration, for a long time, with replacement only after mechanical wear. Practical value. The described method allows using highly porous fillers for biofilters in the process of growing aquaculture objects without their main disadvantage - a rapid decrease in efficiency as a result of pore slagging with biofilm residues. Keywords: RAS, biofilter, filler, restoration, sodium hypochlorite.

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.

biofilters yielding different fillers was established. Clarias gariepinus juvenile was selected as the biological test-object. This species is characterized by increased resistance to the influence of nitrogen compounds, although juvenile individuals at the growing stage of 0.5 to 200 g are more sensi ve to hydrochemical factors. At the same me, this species is less suscep ble to the roundfactor compared to tradi onal aquaculture objects cul vated in Ukraine. It allows working with this species in rela vely small model RAS installa ons. According to obtained results, biofilters with different types of substrates for nitrifying bacteria are undergoing the cycle of biological equilibrium with the same rate at the start-up phase of RAS filtra on. The survival and growth rates of theAfrican sharptooth ca ish juveniles were slightly higher compared to the use of floa ng polymer filler due to more op mal hydrochemical parameters during the opera on of RAS with the biofilter fillers. This can be associated with a higher specific surface area as those in the polymer filler. In order to verify the results of the experiment, especially regarding the effects of different biofilter fillers on water quality, biological equilibrium rate and biological purifica on unit performance in RAS and fish survival, it is advisable to con nue the study with an experimental increase of organic loading.

The paper presents the results of an experiment to assess the effect of different concentrations of vitamin-amino acid complex "Chiktonik" on the growth rate and survival of young African clary catfish (Clarias gariepinus B., 1822) after various stressful situations, for keeping fish in aquaculture. In the experiment, the stressful situation for fish arose due to significant fluctuations in the content of ammonia, nitrites and nitrates in the aquatic environment of a closed recirculation aquasystem, which kept larvae and fry of Clarya catfish during the start of the biological filter, before establishing biological equilibrium in the system. Based on the analysis of sources of scientific and technical information, it was found that the drug "Chiktonik" for more than 10 years is used in animal husbandry to normalize metabolism in animals with unbalanced feeding, after stress, mycotoxin poisoning and antibiotic treatment. This information gave rise to the assumption of the possibility of using the drug in aquaculture, for the same purposes. A series of experiments was performed in a closed recirculating aquasystem, during which the effect of different concentrations of the drug "Chiktonik" in fish feed on larvae and fry of Clarya catfish was tested. It was found that the addition of the drug at the rate of 1 ml per 1 kg of feed accelerates the growth of fish in the experimental variants, compared with the control. Experimental use of high doses of the drug (5, 15, 30 and 45 ml/kg of feed) initially led to inhibition of weight gain of fish, but 10-30 days after the experiment, the growth rate of the experimental material was equal to that of the control group of fish and even exceeded control in the future. The positive effect of vitamin-amino acid complex "Chiktonik" on the survival of young Clarya catfish at the end of the larval period of life and in the early stages of the fry period was established. In an experiment with older fish, which were fully formed fry, such an effect from the use of the drug was not observed: the survival of the fish was at the same level, both in the experiment and in the control. At the same time, it was found that the fry respond less well to high doses of the drug, compared with adult larvae. Thus, the growth rate of fry after the use of high doses of the drug was not equal to that of fish from the control group within a month after the end of the experiment, in contrast to younger fish. In general, the feasibility and safety of the drug "Chiktonik" for young Claria catfish as a feed additive at a dose of 1 ml / kg of fish feed has been proven. It is considered promising to continue research in this direction, using as research material fish of older age groups, including - repair and breeding stock of Claria catfish.

Purpose. To prepare a justification for the use of sodium and potassium salts of humic and fulvic acids (humates) as substances with biologically active properties in fish feeds based on the analysis of sources of scientific and technical information and own experimental materials, Findings. A complex general characteristic of humic substances was provided, the mechanism of biologically active action of humates on living organisms was described. Examples of the use of humates in crop production, medicine, animal husbandry and aquaculture were given. The results of our own studies on the use of humates as a feed additive for valuable objects of aquaculture were presented. Prospects for the inclusion of micro-additives of sodium and potassium humates in the composition of fish feed in order to increase fish survival and digestibility of feed were outlined. Originality. To date, the introduction of humates into fish feed as micronutrients was experimental. The analysis of scientific sources and materials of own studies gave the basis for the conclusion about the need of complex detailed studying of mechanisms of effects of humates on fish. In particular, it is of interest to study the protective properties of humates from the accumulation of heavy metals in the body of fish for the use of micronutrients of these substances in fish feeds. Practical value. The use of humate feed additives in aquaculture will help to solve such urgent problems as the prevention of excessive losses of biological material of cultivated objects, reduction of feed costs, improvement of consumer characteristics of food products. Humates, as substances of natural origin with protective and immunomodulatory action, can become substitutes for some synthetic therapeutic and prophylactic drugs. Key words: aquaculture, humates, compound feed, feed additive, growth rate, survival, feed assimilation.