Aquaculture Conditions Research Articles

Ultrasound examination of the gonads of the african clary catfish in industrial aquaculture

The article is devoted to ultrasound examination of the gonads of the African clary catfish. Data on the state of the reproductive system of fish are the basis for the formation of a high-quality breeding stock. In mature fish, the state of the gonads is an informative indicator and reflects the general physiological state of the body. The object of the study was the African clarias catfish (Clarias gariepinus). A group of 10 individuals, including 5 males and 5 females, was selected for the work. The gonads were examined using the Mindray DP-50 ultrasound machine. A linear ultrasonic sensor was used to assess the gonads of the African clary catfish. The study was conducted in winter 2023. The aim of the work was an ultrasound assessment of the condition, the stage of maturity of the gonads and their variability in females and males of the African clary catfish. A study of the gonads of females, which by age and weight belong to the category of sexually mature, revealed in them the signs inherent in the gonads of the IV stage of maturity. This is typical for fish in aquaculture conditions. Ultrasound diagnostics showed that the gonads of the IV completed stage of maturity, in the upper part isoechoic, are filled with hyperechoic inclusions of high density in the form of oocytes. In the lower medial part there are hypoechoic areas with low density along the entire length of the gonads. The results of ultrasound examination of the testicles of male clary catfish showed that they are of the IV stage of maturity, enclosed in a hyperechoic shell along the entire length. Both testes have a uniform hyperechogenic fine-grained structure of high density. The lobes of both testes are not the same, clearly visualized, increased density. The results of the research allow us to conclude that ultrasound diagnostics of the sex and the study of the gonads of fish can be carried out on an ongoing basis, as it is not only painless, but also a highly informative procedure. For fish species that have lost their ability to reproduce in aquaculture conditions, determining the maturity stage of gonads using ultrasound will allow for scientifically sound hormonal stimulation and fertilization.

Preliminary analysis of pathways and their implications during salinity stress in abalone

Transcriptome sequencing has offered immense opportunities to study non-model organisms. Abalone is an important marine mollusk that encounters harsh environmental conditions in its natural habitat and under aquaculture conditions; hence, research that increases molecular information to understand abalone physiology and stress response is noteworthy. Accordingly, the study used transcriptome sequencing of the gill tissues of abalone exposed to low salinity stress. The aim is to explore some enriched pathways during salinity stress and the crosstalk and functions of the genes involved in the candidate biological processes for future further analysis of their expression patterns.The data suggest that abalone genes such as YAP/TAZ, Myc, Nkd, and Axin (involved in the Hippo signaling pathway) and PI3K/Akt, SHC, and RTK (involved in the Ras signaling pathways) might mediate growth and development. Thus, deregulation of the Hippo and Ras pathways by salinity stress could be a possible mechanism by which unfavorable salinities influence growth in abalone. Furthermore, PEPCK, GYS, and PLC genes (mediating the Glucagon signaling pathway) might be necessary for glucose homeostasis, reproduction, and abalone meat sensory qualities; hence, a need to investigate how they might be influenced by environmental stress. Genes such as MYD88, IRAK1/4, JNK, AP-1, and TRAF6 (mediating the MAPK signaling pathway) could be useful in understanding abalone's innate immune response to environmental stresses. Finally, the aminoacyl-tRNA biosynthesis pathway hints at the mechanism by which new raw materials for protein biosynthesis are mobilized for physiological processes and how abalone might respond to this process during salinity stress. Low salinity clearly regulated genes in these pathways in a time-dependent manner, as hinted by the heat maps. In the future, qRT-PCR verification and in-depth study of the various genes and proteins discussed would provide enormous molecular information resources for the abalone biology.

Nonspecific immune, histology and accumulation of marine worm, Urechis unicinctus in response to bisphenol A (BPA)

Bisphenol A (BPA) is one of the environmental endocrine disruptors, due to its chemical stability it exists in abundant concentrations in water and soil consequently accumulating in the food chain and causing many endocrine-related health problems. So far, studies on the effects of BPA on marine invertebrates have focused on acute toxicity, endocrine regulation, reproduction, and development. However, fewer studies have been conducted on marine benthos. The current study aimed to detect the accumulation of BPA and its impact on tissue structure, antioxidant capacity, and immune indexes in marine worm, Urechis unicinctus. U. unicinctus, as a common marine benthic animal, were exposed to different concentrations of BPA. Blood cells and intestinal tract were taken for tissue structure inspection, and supernatant of the coelomic fluid was collected for oxidative and antioxidant biomarkers. Results showed that the accumulation of BPA in muscles of U. unicinctus tended to increase with exposure time. BPA induced a rise in H2O2 and MDA content, and altered the activities of CAT, T-SOD, GST, LSZ and ACP, weaken the immune system functions. Moreover, pathological observation showed that BPA caused severe histopathology in the respiratory intestine, stomach, and midgut. These results will be helpful to understand the response mechanism of U. unicinctus under BPA exposure and provide a reference for controlling the aquaculture conditions and marine water quality of U. unicinctus.

Temporal patterns of physicochemical and bacteria profiles of static aquaculture systems: insights into health hazards for fish and the public

Knowledge on water quality in static aquaculture systems is crucial to gain understanding of health threats to fish or aquaculture personnel. In the present study, we investigated the temporal profiles of the bacteriological profiles and physicochemical status of static water aquaculture systems (earthen ponds and concrete tanks). All physicochemical parameters measured were within the optimum recommendation. Following microbial analyses in earthen pond water, the TVC and TCC showed temporal variations with concentration increasing with sampling time, however, FCC fluctuated, and 8 bacteria groups were isolated from both rearing enclosures. In which Gram (-) bacteria showed dominance, with 5 Gram negative (Escherichia coli, Proteus spp, Serratia spp, Enterobacter spp and Pseudomonas spp) and 3 Gram positive (Staphylococcus spp, Streptococcus spp, and Bacillus spp) encountered. From earthen pond water, the following microbial occurrences were reported: Staphylococcus spp (20%), Streptococcus spp (12%) Proteus spp (8%) Enterobacter spp (20%) Serratia spp (16%), Bacillus spp (9%), Escherichia coli (8%), Pseudomonas spp (7%). While Staphylococcus spp (18%), Streptococcus spp (16%), Proteus spp (8%), Enterobacter spp (22%), Serratia spp (8%), Bacillus spp (15%), Escherichia coli (8%), Pseudomonas spp (6%) occurred in concrete water. Taken together, although the physicochemical condition raised no well-fare concern, however, the bacteriological profile during this investigation showed potential health risk in static water aquaculture condition or to adjacent aquatic environment from end of production-discharge.

Genetic variability of the endangered fish lake minnow (Eupallasella percnurus) in populations newly established by translocation and those existing long term in Poland.

The lake minnow Eupallasella percnurus is a small leuciscid fish. In Poland, this species has been in a continuous decline since the mid-20th century and is presently considered as a extremely endangered. According to Polish law, E. percnurus is a strictly protected species that requires active conservation measures. In Poland, one the most common and effective measure of active protection E. percnurus is initiation of new populations. For this purpose, in 2004-2012, juvenile individuals originating from aquaculture conditions were translocated to group of isolated water bodies not inhabited by this species. The juveniles were offspring of parental fish belonging to the same local population, which is extinct at present. Five of those attempts were successful. The aim of the present study was to assess the genetic variation in a group new populations and compare genetic variation indicators with 13 old populations that had existed for decades. The polymorphism of 13 microsatellite markers was investigated, significance of differences in the genetic variation indicators between the groups were tested using a one-way analysis of variance (ANOVA). The mean values of all summary statistics under study, i.e. observed heterozygosity, expected heterozygosity and the total number of alleles, were higher in the group of new populations compared to almost all old ones. A similar dependence was found for Garza-Williamson M values, where the mean for the group of new populations was higher than in almost all old populations. Our results indicate that all recently established E. percnurus populations have not yet experienced any extensive founder effects or bottlenecks. They have preserved a large part of the genetic variability typical of their maternal population, which might also have been relatively high. This feature of new populations, may give them a relatively high ability to adapt to changing environments in the future.

ВЛИЯНИЕ РОНКОЛЕЙКИНА НА МОРФОМЕТРИЧЕСКИЕ И ГЕМАТОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ И ФАГОЦИТАРНУЮ И ГЕМАТОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ И ФАГОЦИТАРНУЮ

Cultivated hydrobionts under intensive aquaculture conditions are exposed to stress factors associated with artificial habitats, increased planting density, periodic fishing, etc. At the same time, they experience a decrease in resistance and resilience and an increase in morbidity. A good solution to this problem is the use of immunomodulators. This article presents the results of a study of the effect on fish of the immunomodulator Roncoleukin, which is a dosage form of recombinant human interleukin-2 (IL-2) isolated and purified from yeast cells (Saccharomyces cerevisiae). The subject of the study was the three-year-old Arctic char (Salvelinus alpinus). The evaluation was based on morphometric, hematological (erythro- and leukogram) and cytochemical (lysosomal cation test) indicators. The coefficient of variation of the size and weight parameters of the treated fish was low compared to the con- trol group. This indicates uniform growth of fish fed Roncoleukin, which is a great advantage in fish farming and provides more efficient use of feed. Blood for analysis was taken from the tail vein of the fish in vivo. The results showed a positive effect of the drug on the activation of erythropoiesis and leukopoiesis. There was a significant increase in the proportion of mature segmented neutrophils (the main blood microphages belonging to the non-specific link of cellular immunity) in the leukocyte formula due to a decrease in lymphocytes (specific immunity). An increase in the content of nonenzymatic lysosomal cationic proteins (defensins) in blood neutrophils can indicate a high level of cellular protection of microphages (neutrophils). The results of the study showed a positive effect of the drug Roncoleukin, which can be recommended for use in the ferming of Arctic char.

Histological examination of the young Oncorhynchus mykiss intestines using the feed with chelated and probiotic supplements.

Macronutrient and micronutrient deficiencies in the fish diet can affect fish growth rate, ability to resist disease, and fillet quality. Determination of effective dose of developed feed additives consisting of chelate compounds of biogenic elements and probiotic preparation based on Bacillus subtilis. Young rainbow trout were divided into four groups consisting of 100 fish each. The control group received standard food; the experimental groups received food with chelates and probiotics in different concentrations. At the end of the experiment (30 days), the middle intestine histology and morphometric parameters were studied. The use of chelated compounds alone affected the state of the intestinal villi and the infiltration of the epithelium by lymphocytes. The addition of a probiotic had a positive effect on the migration of immune cells in the intestinal villi; however, the probiotic in high concentrations contributed to a decrease in the number and area of goblet cells. Synergistic effects of chelated compounds and probiotic preparations on the morphometric parameters of the medium intestine were observed. In the proper doses, the studied feed additives might be recommended for rainbow trout farming under industrial aquaculture conditions.

Assessment of the biochemical status of Parasalmo mykiss walbaum in trout farming conditions as a basis for the development of a natural adaptogen based on green microalgae

Increasing the output of aquaculture products is an important condition for supporting food security in Russia and ensuring the socio-economic development of the regions. One of the key factors for the sustainable functioning of trout farms is the timely and effective prevention of the occurrence and spread of diseases in farmed fish [8,10]. The purpose of the presented study was to monitor the condition of rainbow trout based on the assessment of biochemical and morphological blood parameters in age dynamics to identify critical periods and develop an adaptogen from green microalgae for the correction of metabolic processes. In the presented study, the hematological status of rainbow trout was studied in the conditions of the fisheries of the Republic of Karelia. The study was conducted in the summer in 4 age groups. During the research, it was revealed that the age of trout significantly affects the biochemical blood levels studied. As a result of the research, it was revealed that in the studied animals with age there is a significant increase in such biochemical parameters as ALT, Total protein, albumin, and urea. Thus, during the monitoring of the biochemical status of rainbow trout under aquaculture conditions, it was found that the condition of the fish’s body worsens with age, which is reflected in the biochemical parameters of the blood, such as total protein, albumin, and urea. In this case, green microalgae Chlorella can act as a natural adaptogen that normalizes blood biochemical parameters due to the high content of available carotenoids. It has been established that the pigments chlorophyll a (6.68 mg/g) and carotenoids (3.36%) accumulate in noticeable quantities in the biomass of.

Freshwater Monitoring System Design In Real-Time For Fish Cultivation

The increased demand for fish supply in aquaculture highlights the need for sophisticated and accurate monitoring systems to ensure optimal water quality. In this context, Internet of Things (IoT) technology and fuzzy logic have become promising solutions to improve efficiency and effectiveness in freshwater fish farming. This research aims to develop a real-time freshwater monitoring system that integrates IoT and fuzzy logic. This system will enable monitoring of critical parameters such as temperature, pH and water turbidity with a high degree of accuracy. Implementation of IoT sensors that are connected to one centralized network and use fuzzy logic to process the data obtained. The research also involved developing an intuitive user interface to manage the system. The developed system is able to provide real-time monitoring with a high level of accuracy. Users can easily access and analyze the generated data through the user interface provided. The design of monitoring freshwater conditions for intensive aquaculture can be prepared using pH sensor devices, turbidity sensors, and temperature sensors using ESP2866 modules to connect to IoT. From the results of 20 days of system trials, it was found that the system can determine the condition of fresh water with good readings with average level of accuracy for pH sensors of 97%, turbidity sensors of 92% and temperature sensors of 96%.
 
 

Genetic linkage between swimming performance and disease resistance enables multitrait breeding strategies in large yellow croaker

Improving the robustness of fish stock has become a key issue in the advancement of aquaculture, as diseases and harsh aquatic conditions impact industry sustainability and yield. In this study, we identify several genetic loci that link swimming performance to disease resistance in large yellow croaker, and apply genomic selection (GS) for swimming performance to generate offspring with both enhanced swimming performance and disease resistance. First, we classified our reference population as superior swimmers (SS) or inferior swimmers (IS) by swimming tests and assessed inherent disease resistance. Consistent with previous research, SS displayed enhanced resistance to the parasite Cryptocaryon irritans. Through genotyping of parental reference and candidate populations, we generated a single nucleotide polymorphism (SNP) database, containing 45832 high-quality SNPs in total. We applied multitrait genome-wide association study analysis of swimming performance and disease resistance to this dataset and identified three linked SNPs, which were associated with 48 potential candidate genes, including pp3r1b, mapk12b, mapk11, and tnfrsf11a. Next, we generated a GS model using the BayesB method and calculated the candidate population's genetic estimated breeding value (GEBV). Individuals with GEBV's in the top 12 ​% were selected as broodstocks for breeding selective lines (SL), and the remaining individuals were used as the control group (CG). We found that SL exhibited both increased swimming performance and resistance to C. irritans compared to CG. Our study reveals the genetic basis related to swimming performance and disease resistance. This work has implications for designing multitrait breeding strategies and improving whole-fish fitness, both of which are critical in aquaculture.

Microplastic accumulation in oysters: Insights from aquaculture and laboratory conditions

Microplastics, emerging pollutants, are present in seafood and pose a potential health risk to consumers. The objective of this study was to assess microplastic concentrations in the surface water, sediments, and oysters of the Cha Va River, an aquaculture production area in southern Vietnam. Laboratory experiments were also conducted to examine rates of ingestion by and bioconcentration of microplastics in oysters. Microparticles including microplastics were measured in all samples collected from the field, and presented 9–27 items m−3 in surface water, 3300–8000 items kg−1 dry weight in sediments, and 0.67–8.33 items ind−1 or 0.02–0.33 items g−1 wet weight in oysters. Fibre shapes and blue colour were the most common while polypropylene, polyester, polyethylene, and polyethylene terephthalate acrylate, alkyd were identified. The presence of microparticles in surface water and sediment was influenced by the complex vertical motion characteristic of tidal environments whereas the microparticles in natural oysters seemed to be closer related to those in sediment than in the surface water. Laboratory experiments showed that oysters incubated in 10 and 1000 microplastics L−1 tanks accumulated 4.1 ± 2.0 and 19.0 ± 11.0 microplastics per individual, respectively. However, bioconcentration of microplastics in oysters was higher (12.37 ± 6.95) in tanks with lower microplastic concentrations than in tanks with higher microplastic concentrations (0.62 ± 0.35). It is a high potential human health risk to the local oyster-consumers because of the annually microparticle ingestion from 657 to 3942 items per person. We suggested further studies on the severity of this potential health risk and policies for minimising microplastic emissions into the environment in Vietnam.

Linking differences in microbial network structure with changes in coral larval settlement

Coral cover and recruitment have decreased on reefs worldwide due to climate change-related disturbances. Achieving reliable coral larval settlement under aquaculture conditions is critical for reef restoration programmes; however, this can be challenging due to the lack of reliable and universal larval settlement cues. To investigate the role of microorganisms in coral larval settlement, we undertook a settlement choice experiment with larvae of the coral Acropora tenuis and microbial biofilms grown for different periods on the reef and in aquaria. Biofilm community composition across conditioning types and time was profiled using 16S and 18S rRNA gene sequencing. Co-occurrence networks revealed that strong larval settlement correlated with diverse biofilm communities, with specific nodes in the network facilitating connections between modules comprised of low- vs high-settlement communities. Taxa associated with high-settlement communities were identified as Myxoccales sp., Granulosicoccus sp., Alcanivoraceae sp., unassigned JTB23 sp. (Gammaproteobacteria), and Pseudovibrio denitrificans. Meanwhile, taxa closely related to Reichenbachiella agariperforans, Pleurocapsa sp., Alcanivorax sp., Sneathiella limmimaris, as well as several diatom and brown algae were associated with low settlement. Our results characterise high-settlement biofilm communities and identify transitionary taxa that may develop settlement-inducing biofilms to improve coral larval settlement in aquaculture.

Evaluation of quality indices for functional products from fish enriched with selenium in conditions of aquaculture

Scientific and practical aspects are considered for development of functional nutrition products from fish raw materials after lifetime enrichment of the fish muscle tissue with selenium. Size-weight composition is investigated for rainbow golden trout grown in aquaculture, minerals and fatty acids content is determined for hot-smoked products of this species, and quality indicators and nutritional value are evaluated for both raw materials and the products to examine possibility of the enrichment with selenium by adding a selenium-containing preparation to fish feeds and to estimate effect of such feeding on commercial, nutritional and consumer properties of the products. The fish from the experimental group fed by the feeds with preparation Kormogran Selenium-3 had more valuable mineral and fatty acid composition of meat, higher yield of edible parts, and better organoleptic properties of smoked products in comparison with the control group. There is concluded that the lifetime enrichment of the trout tissues with selenium in aquaculture conditions is an effective technology for producing high-quality seafood for functional nutrition.

The usage of probiotic microorganisms in production technology of European grayling fish stock

European grayling is a perspective object of a recreational fishing. In addition, the presence of this species in sufficient quantities in rivers has a positive influence on the formation of the recreational attractiveness of mountain regions, where tourism is one of the main sources of local communities existence. However, grayling stocks in the watercourses of Ukraine are significantly depleted nowadays, and populations are in a condition of lack, what has led to the inclusion of this species into the Red Book of Ukraine. Working out of biotechnologies of artificial reproduction of rare fish species in aquaculture conditions for the further reintroduction of the resulting offspring into natural water bodies takes an important place in the system of environmental protection measures to preserve biodiversity. After all, the reintroduction into nature of artificially obtained fish fry is one of the effective ways to restore the optimal number and structure of rare fish species natural populations, and this, in turn, will allow in the future to restore the limited exploitation of the stock of these fish species. One of the critical artificial fish reproduction technology links is the transfer of larvae to external nutrition. Namely on this stage the highest mortality rates are observed. The usage of live feeds as a starter fodder can significantly improve the situation. Forage organisms, in addition to having high nutritional value, can serve as delivering tools of various targeted products, including probiotics, to a fish larvae organism. The assessment of the usage of probiotic strain Lactobacillus casei IMV B-7280 feasibility is carried, and also the possibility of usage the culture Daphnia magna Straus, 1820 grown in the presence of trehalose lipids, within the technology of early feeding of the European grayling Thymallus thymallus (Linnaeus, 1758). It was shown that the larvae of the European grayling, which received investigated probiotic microorganisms strain, had 15% bigger weight on the final stages of feeding than the larvae of the control group. Introduction to the diet of grown-up grayling larvae of the culture Daphnia magna, previously received of common cultivation with microalgae Desmodesmus armatus (Chodat) E.H.Hegewald 2000 with addition of trehalose lipids, contributed to the reduction of larval mortality and the acceleration of their growth rate. Further improvement of proposed approaches of growing grayling fish planting material can be extrapolated to other fish species and in the future may be applicable in the process of growing rare fish species in conditions of farm aquaculture fish farms, what will allow them to be involved into environmental protection activities by placing appropriate orders. This, in its turn, will contribute to the stable development of communities in rural areas.

디지털 전환 시대의 스마트 양식장 입지 타당성 평가방안 연구

The seriousness of the domestic fisheries industry has fundamental problems, starting mainly due to the depletion of fishery resources, the aging of fishing workers, and the aging of fishing boats and equipment, and the production of coastal fishing (capturing and fishing methods) continues to decline every year due to problems such as illegal overfishing, global warming, and environmental pollution. Despite this situation, global seafood consumption is increasing and the per capita meat consumption is approaching. To this end, a continuous and stable supply system can be established only by further expanding the smart management system that further develops the existing aquaculture industry (farm culture) beyond the traditional fishing method and innovatively improves the inland aquaculture on land. As a result, smart farming will be able to quickly recognize changes in aquaculture conditions, water temperature, and water quality by utilizing artificial intelligence (AI), big data technology, information and communication technology (ICT), and the Internet of Things (IoT), respond to the situation, and engage in stable aquaculture.

Біологічні особливості та перспективи штучного відтворення вирезуба (Rutilus frisii frisii Nordman, 1840) в Україні (огляд)

Purpose. The main goal of the thematic review was the analysis and generalization of literary sources on the peculiarities of its biology, technological aspects of artificial reproduction and growing of vyrezub (Rutilus frisii frisii Nordman, 1840) for the restoration of its natural population in water bodies of Ukraine. To evaluate the perspectives of artificial reproduction and growing of vyrezub in aquaculture of Ukraine. Findings. As a result of human impact on river networks of Ukraine, the abundance of vyrezub significantly decreased, it has become a rare and at the same time an endangered species. According to retrospective data, vyrezub previously belonged to the widespread commercial species of the Dnipro and Southern Bug rivers. The biological features of this species have been analyzed, the observance of which can allow obtaining viable fish seeds in aquaculture conditions. The adaptive possibilities of vyrezub to artificial conditions of reproduction have been reviewed. Historical information on the reproduction of this species over the last century has been analyzed. On the territory of Ukraine, first attempts to artificially reproduce vyrezub were carried out by specialists of Ukrcherrybvod. According to the results of studies of Ukrainian scientists, several stages of artificial reproduction of vyrezub have been identified, namely: taking spawners from natural water bodies, obtaining eggs and sperm, incubation of eggs in incubation devices, obtaining 6 g fish seeds, release of viable juveniles into natural water bodies. However, the works on artificial reproduction of vyrezub were not successful, which was the reason for their complete cessation. In particular, this species is promising for growing in polyculture, as it does not create intense trophic competition with most objects of freshwater aquaculture, and as a result of the consumption of mollusks will reduce the likelihood of the spread of some invasive fish diseases. Practical value. The review of information sources on various aspects of the use of vyrezub in aquaculture will contribute to the development of a system of separate links of the technology of its cultivation for the needs of rearing in the conditions of aquaculture enterprises and stocking of internal water bodies with viable juveniles. Key words: vyrezub (Rutilus frisii frisii Nord­man, 1840), aquaculture, biocontrol effect, artificial reproduction, viable juveniles, stocking, restoration of population abundance.

Біологічні особливості штучного відтворення осетроподібних (Acipenseriformes) видів риб (огляд)

Purpose. To analyze the scientific data of domestic and foreign authors regarding the peculiarities of artificial reproduction of sturgeonss (Acipenseriformes). To investigate the state of study of the phenomenon of polyspermic fertilization in sturgeons and the factors that induce it in the conditions of artificial reproduction and cultivation. Findings. A review analysis of the results of scientific studies by domestic and foreign authors was carried out on the pecularities of artificial reproduction of sturgeons and the phenomenon of polysperm fertilization of their eggs in controlled conditions of aquaculture. It is shown that information on the problems of sturgeon polyspermy and its induction by various factors was practically absent in the available professional literature in recent years. Since during the artificial reproduction of sturgeons, a significant number of embryos have atypical development, which leads to their death even before hatching, it has been suggested that atypical forms of cell division were caused by polyspermy. The conducted studies added to the knowledge about the peculiarities of the structure of the sturgeon egg envelope and the processes that occur during fertilization. Despite the fact that there is a natural mechanism to prevent the possibility of polyspermic fertilization, this phenomenon occurs quite often, causing an impairment of zygote fragmentation at the initial stages of embryogenesis, and therefore a decrease in the yield of larvae. Understaning of the mechanism of blocking polyspermy in sturgeons and the factors that induce it requires further studies. The list of scientific articles includes 61 sources, 58 in English. The published publications mainly cover the period of the last twenty years. Practical value. A review of data from scientific and professional sources on the specified topic will allow a comprehensive approach to the understanding of the peculiarities of artificial reproduction of sturgeons, the phenomenon of polyspermy and increasing the yield of larvae in sturgeon farming. Review material on this topic can be interesting and useful for scientists, practitioners, students whose interests are related to aquaculture and used in the educational process of training specialists in specialty 207 “Aquatic bioresources and aquaculture”. Keywords: aquaculture, sturgeons (Acipen­seriformes), eggs, egg envelope, micropyle, fertilization, cortical reaction, polyspermy, embryos.

Optimum feeding of schemes of beluga (Huso huso L.) at the early stages of ontogenesis in the conditions of industrial aquaculture

Aquaculture is the fastest growing food production industry. The priority direction of freshwater aquaculture is sturgeon breeding. One of the significant stages of the technological cycle of industrial rearing of sturgeons is the maintenance of juveniles during the transition to exogenous nutrition. In industrial fish farming, based on keeping fish under fully controlled aquatic conditions, the use of natural feed is becoming increasingly limited.Despite the use of artificial compound feed, balanced in terms of the main nutrients, only live food serves as a supplier of all biologically active substances, contains proteins that include all essential amino acids, unsaturated fatty acids, vitamins, enzymes and other vital substances, and also helps to increase the activity of all digestive enzymes, causing the overall activity of the body. The article describes the experience of growing beluga (Huso huso L.) in the pools installed in the RAS “Educational and Scientific Complex of Pilot Aquaculture Production” LLP (Uralsk, Kazakhstan).The results of an experiment to determine the optimal feeding schemes for the sturgeon in the early stages of ontogenesis are presented. It has been established that feeding only аrtemia nauplii and decapsulated аrtemia cysts leads to a mass departure of larvae, and analysis of their stomach contents showed that there was no food in them. To facilitate the transition from feeding live food to artificial food, it is optimal to combine different types of live food with pelleted food. The addition of brine shrimp and bloodworms to the diet of dry granulated food contributes to the greatest increase in the growth rate and survival of larvae and juvenile beluga.

The growth of Cheirodon interruptus (Ostariophysi: Characidae) under aquaculture conditions: implications to mitigate the impact of wild stock exploitation in Pampean wetlands

The growth of Cheirodon interruptus (Ostariophysi: Characidae) under aquaculture conditions: implications to mitigate the impact of wild stock exploitation in Pampean wetlands

The technology of growing rainbow trout in the conditions of PE “Western Fish Company” by feeding Vita Fisch compound feed

A study was conducted on feeding Vita Fisch combined feed to rainbow trout Oncorhynchus mykiss this year based on a full-system cold-water farm of the Western Fish Company, Peremyshlyan district, Lviv region. The experiments considered the conditions of keeping hydrochemical and fishery indicators: stocking density, temperature, oxygen saturation, and pH of the environment. At the initial stages of the work, fish pools with a water volume of 30 m3 were treated by a one-time application of the probiotic “Sviteco PW” at a dose of 1.0 ml/m3 of water. According to our observations, after a day, the water in the pool became more transparent compared to collections without probiotics, which indicates high results of bioremediation, which maintains the water body at an optimal level. By conducting production tests on this year's troy ear we set ourselves the goal of producing high-quality, high-nutrition combined feed with a low cost and feed ratio, which are well eaten by fish, contribute to the appropriate growth rate, increase fish weight, profitability of aquaculture, prevention of water pollution, reduction of manifestations of conditionally pathogenic microorganisms and safety for the environment. Therefore, we fed this year's raiyear'srout with “Vita Fisc” granular compound feed, which is made from domestic ingredients according to a recipe for young trout, in specialized production by fermentation of the main components of the meal with the introduction of 2.5 % of the premix and probiotic “Sviteco PWC” production pools under aquaculture conditions at the 0.7 ml/kg feed. The ingredients and production of this feed are focused primarily on quality indicators regarding environmental friendliness and environmental protection, taking into account health, physiological state, the ability of fish to carry loads, the quality of food fish, and the profitability of production. Feeding with combined feed was carried out at a temperature of 8 °C while providing 1 % of the feed from the weight of the fish during the day. As a result of the work, trout have a high activity in eating, digestibility, assimilation of compound feed, and a low feed coefficient of 0.95 k. units were established.