Purpose.To analyze the array of special literature and summarize the information obtained on the features of the white bream (Blicca bjoerkna (Linnaeus, 1758)) and its commercial catch from the Kуiv reservoir. Consider the basic principles of its forecasting, based on the current ecological state of this reservoir, which is of strategic importance for Ukraine.
Findings. An overview of modern scientific publications devoted to the peculiarities of the commercial catch of white bream from the Kуiv reservoir, its forecasting and the prospects for using this species in fisheries is presented. The literature data on the specifics of industrial fishing in the Kуiv reservoir are summarized based on the ecological characteristics of this reservoir. The main factors influencing the adaptation of white bream populations to their commercial exploitation are described. The general directions of the impact of anthropogenic pressure on them and their consequences are considered. The prospects of using white bream as an economically valuable species are shown under the condition of rational industrial fishing in the Kуiv reservoir.
Practical Value. The review can be useful for scientists, applicants, students, government authorities and private entrepreneurs involved in the process of research and commercial harvesting of living aquatic resources in reservoirs, namely in Kуiv reservoir.
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.
Purpose. Investigate ecological conditions and determine fish productivity of ponds when growing young-of-the-year carp using a suspension of chlorella.
Methodology. During the study, we used methods generally accepted in hydrochemistry, hydrobiology and fish farming.
Findings. The article presents the results of the study on the use of chlorella suspension in the cultivation of carp. It was found that the use of chlorella suspension created favorable hydrochemical conditions resulting in intensive development of zooplankton, which had a positive effect on the growth of young-of-the-year carp and fish productivity of the pond. The development of the natural food supply was sufficient to meet the nutritional needs of juvenile carp. The average seasonal biomass of zooplankton in the experimental pond was 28.68 g/m3 that was 1.5 times higher than in the control. The share of cladocerans in the total biomass of zooplankton in the experimental pond was 76.6%, versus 36.8% in the control. The average biomass of zoobenthos for the growing season in the experimental was 1.3 times higher than in the control, and was formed by chironomid larvae, which are valuable in the food chain.
Originality. The study investigated ecological conditions and fish productivity of growing ponds under conditions of the application of cattle manure and suspension of chlorella when growing carp in monoculture.
Practical value. It was found that the use of chlorella suspension promotes the intensification of the development of zooplankton organisms in ponds. The obtained data can be used to develop practical recommendations for optimizing the conditions for growing carp seeds and increasing the biological productivity of ponds.
Purpose. To evaluate the reproductive indicators and exterior characteristics of the breeding brood stock of the Galician carp group at the original farms, namely farms "Korop" and "Dzherelo", State Enterprise "Lviv Experimental Station".
Methodology. The study was conducted according to generally accepted methods in fish farming and breeding using statistical processing and data analysis. The productive features of the Galician carp were improved by the method of mass selection and directional selection. The tasks of the selection were to obtain a breeding stock of the Galician group, which will ensure the production of offspring with high individual weight in the first year of life.
Findings. The age of maturity in brood Galician carp was 3-4 years in males and 4-5 years in females. After pituitary stimulation in the conditions of industrial reproduction, a positive reaction of the brood fish was established, which exceeded 92%.
When forming breeding stocks of Galician carp in the first year of life, the intensity of selection was 15%. Directional selection on the basis of average individual weight started on the second year of life. The intensity of selection of age-1+ Galician carp group was 50%, then this parameter exceeded 85%.
Reproduction of the Galician carp group occurred in spawning ponds and in industrial conditions. Working fertility of females was 1256.0 ± 132.80 thousand eggs, relative fertility - 127.5 ± 5.52 thousand eggs/kg, which was quite high in comparison with the Ukrainian framed carp. During the reproduction of Galician carp in ponds, the yield of three-day-old larvae from one nest amounted to 241 thousand individuals.
According to the obtained data, based on the exterior indicators, the Galician carp group is characterized by a high-backed physique and fleshy structure, which is preserved throughout life.
In view of the conducted study, the Galician carp group fully complies with the requirements of the Regulation on approbation of selection achievements in animal husbandry and can be submitted to the relevant authorities for consideration and approval as an intrabreed type of Ukrainian framed and scaly carp breeds.
Originality. The analysis of reproductive indicators of the breeding brood stock of Galician carp will serve as a basis for the presentation of this group in the status of intrabreed type and its approval as a selection achievement.
Practical value. The obtained results will contribute to the expansion of the Galician carp group both in the aquaculture of Ukraine and abroad. Breeding brood material as an object of selection will be involved in work with framed carp mixes.
Purpose. Analysis of productive and economic indicators in the cultivation of age-1+ carp as a result of the use of prebiotics based on mannan oligosaccharides (MOS) in feeding.
Methodology. Four ponds were used, two of which were experimental and two control ponds, which were stocked with age-1 scaly carp with an average weight of 76–77 g at a stocking density of 2200 specimens/ha. Fish of Experiment 1 and Control 1 were fed with extruded feed with a protein content of 23%, fish in Experiment 2 and Control 2 were fed with a grain mixture with a protein content of 19%. 0.05% prebiotic based on MOS "Actigen" was added to the diet of experimental groups of carp throughout the growing season. Optimal conditions for carp farming were ensured including control over oxygen, hydrochemical and hydrobiological regimes in ponds, which were measured according to the generally accepted methods in fish farming. Fishery and economic indicators of growing age-1+ were determined after harvesting fish in autumn.
Findings. Major hydrochemical parameters in all ponds were within the normative values. The average seasonal biomass of forage organisms of zooplankton and zoobenthos during the growing season did not differ in the experimental ponds and amounted to 10.33-16.23 g/m3 and 1.23-2.96 g/m3.
A positive effect of the use of prebiotics based on MOS in the feeding of age-1+ carp was established. When the prebiotic was given as a part of the extruded feed, the average weight of fish was higher by 11.5%, and fish productivity by 22.7% relative to the control group, while the cost of feed for cultivation was lower by 20%. When it was added to the grain mixture, these values were higher by 12.9%, 16.3% and 16.7%, respectively.
The profit, as a result of the use of the prebiotic based on MOS in the composition of the extruded feed increased by 43.3% compared to Control 1, and by 19.1% compared to Control 2 when it was added to the grain mixture.
Originality. For the first time, a comparative analysis of the effectiveness of the use of the prebiotic based on MOS in the composition of extruded feed and grain mixtures was performed taking into account productivity and economic indicators.
Practical value. The obtained results indicate the feasibility and effectiveness of the use of prebiotics based on MOS in the feeding of age-1+ carp. Introduction of experimental additives to feeds of different composition helps to obtain additional growth and increase the economic component in the cultivation of carp to marketable condition.
Purpose. The aim of the work was to study certain morpho-physiological parameters of carp as a result of additional introduction of a mycotoxin sorbent to a feed with signs of spoilage.
Methodology. During 2019–2020, two experiments were conducted in the laboratory. The first one included 7 groups-analogues of age-1+ Nyvky carp, 20 fish in each group, with an average weight of 22.5 g. The control group of fish was fed for 24 days with a compound feed with signs of spoilage, «Mykosorb» was additionally added to the diet of the experimental groups in the amounts of 0.05, 0.1; 0.15; 0.2; 0.25 and 0.4%, respectively. The second group included 4 groups of age-1+ fish, 12 fish in each group, with an average weight of 20.0 g. The diet of the control group was identical to that of the first experiment, and the experimental groups with the addition of 0.05, 0.075 and 0.1% of «Mycosorb», respectively. During the study, optimal conditions for keeping fish were provided. Fish after were measured and weighed at the end of the experiment and their weight gains were analyzed according to generally accepted methods in fish farming. The activity of antioxidant enzymes and the content of lipid peroxidation products depending on the composition of the diet were studied.
Findings. The studies used compound feed with signs of spoilage as a result of violation of their storage technology, which identified three groups of toxins: Aflatoxin B1, Zearalenone and Deoxynivalenol.
As a result of the first stage of the study, the rates of application of mycotoxin sorbent into the diet of carp at amounts of 0.05 - 0.2% were determined. At the same time, there was no clear proportional pattern of changes in the average weight of fish depending on the amount of introduction of «Mycosorb», the value increased in all experimental groups compared to the control by 0.4 – 15.2%. Muscles of age-1+ fish were found to have higher (p<0,001) catalase activity after application of 0.15% of the test drug by 1.4 times, 0.2% — by 46%, 0.25% — by 69 and 0.4% — by 79%. Superoxide dismutase activity also increased, except for the groups of 0.2, 0.25 and 0.4% of «Mycosorb». There was a tendency of 21.0 and 22.6% decrease in the content of diene conjugates as a result of feeding 0.05 and 0.1% sorbent and some increase as a result of feeding 0.15; 0.2; 0.25 and 0.4% additives.
Studies of the next stage showed that addition of «Mykosorb» at the rate of 0.05, 0.075 and 0.1% to the feed, the average weight of age-1+ carp in the experimental groups increased by 45.4; 37.2 and 30.3%, the condition factor — by 41.9; 40.8 and 42.7%, the relative growth rate is 4.3; 5.9 and 4.6 times, respectively. The fish body height to length ratio was lower by 10.3, 7.0 and 7.4% relative to the control group. Addition of 0.05, 0.075 and 0.1% of «Mycosorb» increased resistance of fish due to an increase in the hepatopancreatic activity of antioxidant enzymes: superoxide dismutase by 28.3, 30.5 and 5.0% and catalase by 56.5 (p<0.001), 55.5 (p<0.001) and 46.3% (p<0.05). At the same time, addition of 0.05 and 0.1% of «Mykosorb» increased the content of diene conjugates by 11.3 (p<0.01) and 12.3% (p<0.01), TBC-active products by 19.7 (p<0.05) and 13.2%.
Originality. For the first time, the feasibility of addition of the mycotoxin sorbent «Mykosorb» into the feed with signs of spoilage was studied. The effect of feeding age-1+ carp with diets of various compositions on some morpho-physiological parameters of carp in the conditions of model tests was carried out.
Practical value. Additional weigh gains and improvements of the antioxidant defense system of the carp organism were observed. The use of «Mykosorb» in carp feeding allows reducing the negative impact of low quality feed on fish body.
Purpose: To analyze the specialized literature and summarize the information on the main parasitic diseases of whitefish.
Findings: Whitefish are members of the Salmoniformes, which are currently represented by 3 subgroups (Salmonidae, Coregonidae, Thymallidae). Whitefishes are widespread species of fish in the subarctic and boreal zones of Europe, Asia and North America and are the most important components of the ecological system and valuable objects of local and industrial fishery. But these fishes are frequently affected by parasitic diseases. This article contains the description of most common parasitic diseases of whitefish and of the main causative agent, clinical signs of diseases, and the main preventive measures to prevent the occurrence of these diseases in whitefish culture. Aquaculture of whitefish creates a competitive food production for one or two fattening seasons with their delicacy gastronomic benefits and high economic profitability. Products of whitefish are popular on external markets that is also a good motivation for improvement of the biotechnological development for various methods of cultivation of these valuable fish. However, with increasing amounts of production, transporting fish from one farm to another and crowded stocks of fish result in problems with diseases of different etiology. The above material describes main parasitic diseases that occur in whitefish including their main symptoms, which will help to identify them in time.
Practical value. Information on the main parasitic diseases of whitefish was systematized. Most of the parasitic diseases known to the whitefish are ectoparasitosis. These are ichthyobodosis (costosis), trichodinosis, chylodonelosis, ichthioftirioz, trichophthirioz and cruciformis. Proteocephalosis, acanthocephalosis, diplomystomosis are the most dangerous among helminths. The short characteristic of these diseases is described and the methods of prophylaxis of these diseases are suggested. The review can be useful both for scientists dealing with the problem of whitefish acclimatization on the territory of Ukraine and for fish breeders already engaged in the whitefish aquaculture in Ukraine and abroad. Descriptions of symptoms of diseases will be useful for preliminary diagnostics of diseases.
Purpose. To estimate the parameters of infestation of Helix aspersa by nematodes, experimentally identify the optimal concentration of anti-helminthic drugs and assess their effectiveness.
Methodology. The experimental work on the development of therapeutic measures against nematodes of Helix aspersa (Müller) lasted for 15 days. The results of the experiments were evaluated by the following indicators: extensiveness and intensity of parasite infestation; survival of mollusks,%. Feeding activity was assessed by the relative amount of feed the mollusks ate per day. At the beginning of the experiments, histological examinations of mollusk tissues were performed. Selected samples were preserved in 4% formalin solution and then histological sections were made, which were than frozen with subsequent staining with hematoxylin-eosin. Histological analysis was performed using a light microscope at 8x and 40x magnification and a Sciencelab T500 5.17 M photographic digital camera. Assessment of changes in the histostructure was performed visually and using morformetric analysis on mollusk intestine samples. Two variants of the experiment with albendanzole (variant № 2 and 3) and control were evaluated.
Findings. According to the results of the experiments, the best indicators of the anthelmintic effect and survival of snails were obtained using albendazole added to compound feed at a concentration of 0.02% of the live weight of mollusks. At this concentration, complete destruction of mature individuals of Alloionema appendiculatum was noted, as well as a decrease in the infection of snails with helminth eggs from 100% to 10%. The study of the histostructure of tissues and organs of mollusks showed that the use of albendazole at concentrations of 0.01% and 0.02% did not cause noticeable pathological changes in the muscles and brain of mollusks. However, certain structural abnormalities were observed in the cells of the intestinal and liver epithelium, which were detected as vacuolization of the cytoplasm, destruction of cell membranes, lysis and pycnosis of nuclei. The relative number of such cells with the pathology was about 10-15% when using 0.01% albendazole, and increased to 30-50% when using albendazole at a concentration of 0.02% of the live weight of snails. No noticeable anthelmintic effect was found when using trematozole.
Scientific novelty. For the first time, the therapeutic effect and the optimal scheme of deworming of mollusks Helix aspersa infected with the parasitic nematode Alloionema appendiculatum were determined experimentally.
Practical significance. The obtained results are of interest to enterprises engaged in snail farming.