Valuable Fish Species Research Articles

Establishment and characterization of SSI cell line from Sebastes schlegelii intestine for investigating the immune response to Pathogenic Bacteria.

As a commercially valuable fish species, Sebastes schlegelii faces threats from pathogenic bacteria like Edwardsiella piscicida during aquaculture. The global host range of E. piscicida encompasses various species, yet its pathogenic mechanism remains incompletely elucidated. Cell lines offer invaluable in vitro resources for studying the pathogen pathogenicity. Here, we established and characterized a cell line derived from the intestinal tissue of the S. schlegelii, designated as SSI. SSI has undergone continuous subculturing for over 80 passages, demonstrating robust growth in DMEM supplemented with 10%-20% FBS and 20 μM HEPES at 24°C. Karyotype analysis and 18S rRNA amplification confirm its origin. SSI exhibits high transfection efficiency for exogenous DNA, making it suitable for gene expression and intestinal function analysis. E. piscicida infects SSI cells at low densities without inducing morphological changes within 6h of infection, suggesting the potential of SSI as an in vitro model for studying E. piscicida pathogenicity. This cell line provides a valuable tool for investigating mucosal immunity and E. piscicida pathogenic mechanisms in marine fish.

ERMƏNİSTANIN AZƏRBAYCANA QARŞI EKOLOJİ TERRORU

Since 1988, 20% of Azerbaijan's lands have been occupied as a result of the war waged by Armenia to pursue its territorial claims against Azerbaijan. After a long occupation, during the 44-day Patriotic War and 24-hour local anti-terrorist operations, our lands, which had been in the hands of the enemy for almost 30 years, were liberated by our brave Army. However, in the territories we liberated from occupation, the enemy left behind ruins and an environmental disaster. For almost 30 years, Armenia deliberately tried to destroy our nature, carried out environmental terrorism against Azerbaijan, spontaneously exploited natural resources, including our occupied territories, polluted drinking water reservoirs with industrial waste, and disrupted the ecological balance of the environment. During the occupation, the enemy committed the great¬est acts of vandalism on our lands; the occupying forces destroyed forests, national parks, nature reserves, valuable trees and other rare examples of biodiversity. The rivers that are the source of Azerbaijan's drinking water are contaminated with chemical, biologi¬cal and other radioactive waste flowing from the territory of Armenia. Over the past years, contamination of water sources flowing from the occupied territories has led to the death of valuable fish species and the depletion of fish stocks. 7 ecologically important relic lakes and 10 reservoirs in the liberated territories of Azerbaijan were subject to serious anthropogenic impact from the occupying Armenia.

The use of aquatic bioresources as a factor in ensuring Ukraine’s food security: legal aspects

The article is dedicated to the study of the legal aspects of using aquatic bioresources in Ukraine and the impact of their usage on ensuring the country’s food security. It is argued that the issue of proper legal regulation of the use of aquatic bioresources is becoming increasingly relevant today. Attention is given to both legislative and scientific approaches to the issue of legal regulation of Ukraine’s food security. The necessity of adopting a separate law titled «On the Fundamentals of Food Security of Ukraine» is emphasized. It is noted that the state’s food policy should aim for the highest degree of self-sufficiency, as the quality and quantity of consumed food products directly impact the nation’s health, life expectancy, work capacity, and intellectual potential. The article examines the legal grounds for the usage of aquatic bioresources. The impact of the fishing industry on ensuring Ukraine’s food security is analyzed, with the conclusion drawn that the country’s food security largely depends on the state of aquatic bioresource usage. The level of fish consumption and its processed products serves as an indicator of the population’s food security, which should be maintained at a level conducive to physiological needs. It is stressed that the development of the fishing industry is one of the most important tasks for ensuring the post-war recovery of the country. The article identifies aquatic bioresources as a strategic state food reserve in the current context. The artificial reproduction of valuable fish species is aimed at both supporting aquatic ecosystems and building industrial stocks. The author asserts that today, food security is a condition for maintaining the state’s sovereignty, supporting high levels of public health, and developing the country’s economy. Emphasis is placed on the fact that the use of aquatic bioresources is crucial for the country in terms of ensuring food security, improving economic conditions, saturating the domestic market with quality food products, increasing employment and welfare, as well as preserving biodiversity and effectively using water and hydrobiological resources.

Assessing the potential ecological and human health risks of trace metal pollution in surface water, sediment, and commercially valuable fish species in the Pashur River, Bangladesh.

This research examines the contamination levels in the Pashur River in Bangladesh stemming from trace metal discharge originating from the Mongla seaport and various industrial outlets. It delves into both ecological risks and potential health hazards for humans consuming fish carrying accumulated trace metals. The research employed atomic absorption spectrometry to measure the concentrations of chromium (Cr), arsenic (As), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), and cadmium (Cd) in surface water, sediment, and fish samples. Target hazard quotient (THQ) and carcinogenic risks were calculated to determine the human health risk caused by the consumption of these targeted fish species. An RI value of 42.89 indicates that the collective presence of trace metals in sediment poses significant ecological risks to the study area. Although the majority of trace metals present in sediment are categorized under class 1 (ranging from unpolluted to moderately polluted) based on the Igeo values, Cd is classified under class 2, signifying a moderate level of pollution. Significantly, THQ values surpass the threshold of 1 for Cr and As, indicating potential health risks associated with the consumption of specific fish species. Among the trace metals analyzed, Ni demonstrates the highest cancer risk (CR) value, at 5.78 × 103, indicating a notable cancer risk associated with the consumption of targeted fish. Recommendations include the strict enforcement of waste disposal policies to mitigate anthropogenic discharge and safeguard the river from further pollution.

Fisheries and biological characteristics and state of stocks of the main commercial fish species in Beloye Lake

The current composition of the ichthyofauna and the importance for fisheries of the main fish species in Beloye Lake (Vologda Region) is described in the article based on research materials from 2018 – 2022. The biological features and commercial use of twelve most valuable fish species are summarized as result of the composition of industrial and research catches studies. The size and age composition of catches, the age of puberty, the timing and conditions of spawning, and the feeding patterns of fishes were studied. The influence of net fishing gear with different mesh spacing on commercial fish populations and the magnitude of nets fishing productivity (fishing effort) were studied for the first time. The role of the most important fish species for industrial fisheries in Beloye Lake was assessed.

Discriminating the origin of fish from closely related water bodies by combining NMR spectroscopy with statistical analysis and machine learning

Pikeperch, perch and bream are among the most traded and valued fish species in North-Eastern Europe. Therefore, it is necessary to be able to distinguish fish from different lakes and coastal sea regions to ensure a good traceability of products in the fish market and to protect both consumers and fish stocks. Untargeted metabolomics using nuclear magnetic resonance (NMR) spectroscopy is a suitable tool for this purpose. It is an established method for determining various properties of biological and living systems, such as health, origin, type, etc. Statistical methods including principal component analysis (PCA) and linear discriminant analysis (LDA) are typically applied to NMR data to correlate spectra with a particular research question.Herein we examine fish from three closely related water bodies and demonstrate that reliable determination of the water body that a particular fish originates from by traditional statistical analysis (PCA and LDA) of fish NMR spectra is not possible. In contrast, determining the fish species is possible. We proceed to show that machine learning methods perform better and that a combination of statistical analysis (LDA) and random forest (RF), a supervised machine learning technique, allows reliable determination of the originating water body, while being also tolerant to seasonal variations. This is an improvement over prior work, which has dealt with more clearly distinguished origins of fish. Exceptional accuracy was achieved in correctly assigning fish to their origin even in a scenario where two of the water bodies are connected by a river through which the fish are known to migrate. Since determining the origin of fish is important in environmental protection, we recommend following up this approach and using it as the basis of a robust tool for environmental protection and other monitoring purposes.

Study on the relationship between economic input growth in Marine protected areas and environmental governance in the North Pacific Coast of Costa Rica: Based on reef fish assemblages

Reef fish communities under fishing pressure often experience reduced biomass, abundance, and altered size structure. The establishment of marine protected areas (MPAs) can help mitigate these declines. However, the success of MPAs, especially in developing countries with financial and socioeconomic challenges, largely hinges on effective enforcement. This study utilized underwater visual surveys (UVS) and baited remote underwater video stations (BRUVS) to evaluate population density, size distribution, and biomass of both economically valuable (e.g., target and ornamental species) and ecologically important (e.g., small/large predators and herbivores) fish groups within and outside a no-take MPA on the northern Pacific coast of Costa Rica.The results indicated that protective measures did not significantly affect the biomass of economically valuable fish species. However, there were notable differences in fish abundance and size distribution between no-take zones (where fishing is prohibited) and open-fishing zones. This suggests that, despite potential illegal fishing activities within the MPA, certain fish community components benefit from the protective measures.Specifically, herbivores and ornamental fish, which are often targeted by artisanal compressor fishing and the aquarium trade, exhibited higher biomass and abundance levels within the MPA. Additionally, significant shark species such as Galeocerdo cuvier, Carcharhinus leucas, and Carcharhinus limbatus were exclusively found within the MPA.The study also highlighted the crucial role of habitat quality, particularly high coral cover, in enhancing the biomass of ornamental fish.This research contributes to the growing body of evidence that MPAs, even with limited enforcement, consistently offer ecological benefits for reef fish communities

Evaluation of the safety, immunogenicity and protective effect of an attenuated Pseudomonas plecoglossicida strain ΔgacS as the live vaccine for the large yellow croaker (Larimichthys crocea)

Pseudomonas plecoglossicida is one of most important pathogenic bacterial species in large yellow croaker and several other commercially valuable fish species. In our previous study, a GacS deficient mutant (ΔgacS) was constructed and its virulence showed substantially attenuated. In present study, the safety, immunogenicity and protective effect of the ΔgacS were evaluated in large yellow croaker as a live-attenuated vaccine candidate. It was shown that the ΔgacS strain exhibited good safety to large yellow croaker and there was no mortality or clinical symptoms observed in all fish that infected by ΔgacS strain with the doses range from 2 × 105～107 CFU per fish via intraperitoneal injection (IP) or immersion (IM), and almost all bacteria were cleaned up in the spleen of the fish at 14-day post infection. Specific antibodies could be detected at 7-day and 14-day post infection by direct agglutination method, and the valences of antibodies and bactericidal activities of the serum were significant increased with vaccination doses and vaccination time. Moreover, the expressions of some molecules and cytokines involved in specific immune responses were detected in the ΔgacS strain immunization group and control group. After challenged by the wild-type (WT) strain XSDHY-P, the relative percentage survival (RPS) showed highly correlated with the immunized dosage regardless of vaccination methods. It showed that the RPS of the IP groups were 39.47 %, 57.89 %, 71.05 % with the immune dosage in a descending order, respectively, and the RPS of the IM groups were 26.31 %, 36.84 %, 76.31 % with the immune dosage in a descending order, respectively. In summary, the ΔgacS strain exhibited safety and good protective effect to large yellow croaker and was a potential live vaccine candidate.

Occurrence of microplastics in commercial fish species from the Ethiopian rift valley's Lake Hawassa, Ethiopia.

Microplastics (MPs) have recently been detected as emergent pollutants in the Ethiopian rift valley lakes located close to rapidly expanding towns. We provide the first study of MPs ingestion of commercial fish species from Lake Hawassa, Ethiopia: Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus). A total of 60 individual fish species was collected from three sampling sites of lake Hawassa in October 2020. Across all sampling sites, there was a significant difference in ingested MPs between benthic omnivore catfish and pelagic phytoplanktivorous Tilapia (χ2 = 15.864, p < 0.001). The most common size of ingested MPs (84.6%) was 0.5-1mm, with fragments (59.5%) dominating, followed by fibers (25.4%). On average, 4.03 ± 1.33 MPs with sizes ranging between 60μm and 10.53mm were detected per individual. White and yellow MPs were particularly numerous, accounting for 36.8% and 26.4% of the total, respectively. Because Lake Hawassa's fishery is so significant, the potential impact of MP pollution on the lake biota in general, and economically valuable fish species in particular, deserves attention, additional research, and, if possible, early mitigation.

Physiological and biochemical studies of young sterlet sturgeon (Acipenser ruthenus L.) in the lower reaches of the Volga river

In conditions of a decrease in the number of rolled sturgeon larvae in the lower reaches of the Volga River, an urgent issue is the study of the physiological and biochemical parameters of the fish organism. The purpose of this work is to conduct physiological and biochemical studies of juvenile sterlet (Acipenser ruthenus L, 1758). The study of fish was carried out using the methods of classical histology and biochemistry. The degree of damage to the gills and liver was assessed on a scale from 1 to 5 points. The content of total lipids and water-soluble protein in the muscle tissue of sterlet fingerlings was studied as biochemical parameters. The morphological picture of the gills of 80% of the fish corresponded to a weakly pronounced character of changes (2 points), while in others it was characterized by the presence of a borderline state between weakly pronounced changes and moderate injuries (2–3 points). Six types of disorders were found in the gills: hyperplasia of the respiratory epithelium of lamellae, dilation of the blood vessel of the filament, goblet-shaped swellings of the apical part of the filament, invasions, expansion of the apical part of the lamellae, proliferation of connective tissue of lamellae. In the liver of 80% of fish, a borderline state was recorded between mild changes and moderate damage (2–3 points), in 13.3% of individuals the liver had mild damage (2 points), in 6.7% there were medium damage (3 points). Four types of disorders were found in the liver of juvenile sterlet: fullness of the liver capillaries, pronounced venous fullness, cavities, capillary dilation. In the muscle tissue of fingerlings, the concentrations of total lipids were in the range of 1.39–5.28%, and water-soluble protein — 45.59–57.97 mg/g. The study of the physiological and biochemical parameters of juvenile sturgeon in the lower reaches of the Volga River is very important for the biology of the species and monitoring the natural reproduction of these valuable fish species.

Improved breeding and seed production of climbing perch (Anabas testudineus) in controlled tanks and cage systems

The climbing perch (Anabas testudineus) is a valuable fish species with significant potential for aquaculture. However, a low survival rate was observed at its early development stages, requiring an optimized protocol for sustainable aquaculture production. This paper presents an improved breeding and seed production technology for climbing perch. Mature climbing perch were induced to spawn using salmon gonadotropin-releasing hormone analog (sGnRHa) at a dose of 30 µg/kg-1 body weight of the breeder. The female broodfish spawn 9–10 hours after hormone injection. Developmental stages were defined based on the morphological features of the embryos from the first cleavage to the hatching stage. The first cleavage began at approximately 18–20 minutes after fertilization. Newly hatched larvae were observed within 18–20 h at 30°C, having an average larval size of 0.389±0.042 mm (total length). Successful breeding entails a selection of suitable algal species, an optimal aquaculture environment, regular feeding rates, consistent monitoring of larval development, and effective management of water quality. Survival rates from the larval stage to fry were achieved at 84.69% and 77.60%, respectively, while the survival rate to the fingerlings stage was 72.51%. Therefore, by implementing an optimized protocol, aquaculture practitioners can maximize the production potential of climbing perch while ensuring sustainable cultivation practices. The findings from this research contribute to the advancement of climbing perch aquaculture by providing valuable insights for the successful cultivation and increased economic profitability of A. testudineus species in hatchery productions.

Развитие интеграционных формирований рыбоводных хозяйств в Белгородской области

Modern commercial fish farming in Russia is mainly represented by small enterprises. However, in the Central Federal District, and above all in the Belgorod Region, objective conditions have now been created that allow for the processes of concentration of production (with its simultaneous specialization) on the basis of the creation of new management and production structures (corporate associations), taking into account regional peculiarities of production placement and cooperative relationships. There are such favorable conditions in commercial fish farming in the Belgorod region. Being in favorable natural and climatic conditions and using modern biotechnics and fish growing technology, favorable opportunities have developed in the Belgorod regions for the introduction of a cluster production system for the cultivation of high–value fish species (sturgeon, salmon). It is important to create well-managed companies with the participation of heads of local authorities and qualified specialists.

Age, Growth, and Mortality of Pontic Shad, Alosa immaculata Bennett, 1835, in the Danube River, Romania

This study aimed to evaluate the growth, mortality parameters, and exploitation rate of Pontic shad, Alosa immaculata Benett, 1835, in the Danube River, Romania (km 169–197). The sampling collection started with the first signs of Pontic shad migration, on 4 March 2023, and continued weekly until the beginning of June 2023, when the last specimens were caught in the nets. The estimation of the growth, mortality parameters, and exploitation rate was done in FiSAT (FAO-ICLARM Stock Assessment Tools). The von Bertalanffy growth equation was estimated at L∞ = 36.75 cm, the growth coefficient was k = 0.68 year−1, and the theoretical initial age was t0 = −0.67 year−1. The total mortality rate (Z) estimated was 2.76 year−1, with a natural mortality rate (M) and fishing mortality rate (F) of 0.89 year−1 and 1.87 year−1, respectively. The Z/k ratio was found to be 4.11 and the exploitation rate (E) was estimated at 0.68 year−1, indicating the overexploitation of Alosa immaculata stocks. In conclusion, this study provides valuable insights into the population dynamics of Pontic shad in the Danube River, Romania. The assessments of the growth parameters, mortality rates, and exploitation rates highlight a level of overexploitation of Alosa immaculata stocks. These findings underscore the importance of applying effective fishery management strategies to ensure the sustainability and conservation of this valuable fish species in the Danube River ecosystem.

Assessing the euryhaline characteristics and metabolic responses of meagre (Argyrosomus regius) when reared under different salinities: Opportunities for aquaculture refinement

The aquaculture of meagre (Argyrosomus regius), a commercially important fish species, is still under development towards its full potential and optimized production. While its key strengths in fish farming, including high growth rate, efficient feed conversion ratio, superior flesh quality, nutritional value, size, and established husbandry techniques, are well-known, further scientific research can unlock additional rearing opportunities for this species. As migratory fish, meagre spends its early life stages in estuaries before moving to coastal and offshore areas, experiencing diverse environmental conditions that significantly influence its feeding behavior, growth, and reproduction. Despite its adaptability, meagre production has been limited to sea cages and land-based salt ponds. Considering its high tolerance to a wide range of factors, particularly salinity, the present study aimed to evaluate the stress and biochemical costs associated with rearing meagre fingerlings under hypo-osmotic environments. The objective was to enhance aquaculture practices and explore the possibility of cultivating this species in more diverse locations without compromising productivity. Meagre fingerlings were reared under different salinities for 28 days, namely at 5, 10, 20, and 30 PSU. Growth rate was calculated, and biochemical responses associated with oxidative stress and energy metabolism were measured in muscle, liver, and heart tissues. Meagre fingerlings displayed remarkable euryhaline characteristics at the biochemical level, as evidenced by their limited response to the varying salinity conditions. An increase in oxidative stress responses and energetic demand was found, together with higher growths, at higher concentrations (20 and 30 PSU), farther from the meagre isoosmotic concentration (∼10 PSU). Understanding these biochemical responses enhances our knowledge of aquaculture techniques and paves the way for adapting and expanding operations to diverse environmental conditions and practices. By leveraging the euryhaline potential of meagre, this research contributes to the sustainable growth of the aquaculture industry while offering new perspectives to produce this valuable fish species.

Regularities of oogenesis and spermatogenesis of commercially valuable fish species in the water bodies of the Dagestan part of the Middle Caspian Sea

Based on our own research and literature data, it was proved that the features of vacuole location, size, and variability in the periods of early and late trophoplasmic growth require the closest attention. There are also certain inconsistencies of gametogenesis between different species of fish within the family. These consist in the fact that for fish species that have a shorter spawning period (roach, pike and perch), the general specificity of the annual cycles of development of the sex glands is characterized by the absolute termination of spermatogenesis by the period of the beginning of spawning, the absence of maturation or new formation of sexual products in this process. Individuals with extended spawning (for gouster and silver carp) are characterized by such features as the presence of an additional wave of spermatogenesis, which begins and ends during the spawning period, the incomplete development of sexual products by the beginning of spawning and the continuation of the process of their maturation in individual cysts of the testes throughout the spawning period (for bream and fish), continuous spermatogenesis,which allows the use of reproductive products at any time from spring to fall of the annual cycle, and under favorable conditions — throughout the year (for carp and catfish). In the experimental aspect, the obtained results can be applied in conducting a large-scale selection of female fish, based on the size of ovulated oocytes and individual selection according to the average statistical size of the latter. In fishery plan the above mentioned is required in connection with obtaining eggs from fish with batch spawning and asynchronous development of oocytes.

Recent global climate change effects: A study of Eleutheronema rhadinum in Chang-Yuen Ridge, Taiwan

This study investigated the potential effects of climatic oscillations on CPUE of Eleutheronema rhadinum (East Asian fourfinger threadfin), a commercially valuable fish species in East Asia. Fishery data from Chang-Yuen Ridge between 2015 and 2022 was analyzed in conjunction with four climatic oscillation indices that were lagged by up to 5 years. The results revealed a fluctuating CPUE associated with the 1-year-lagged Ocean Niño Index (ONI lag 1) and 1-year-lagged Southern Oscillation Index (SOI lag 1) suggesting a potential effect between climatic oscillation indices and East Asian fourfinger threadfin CPUE. These findings can provide insights into the association between East Asian fourfinger threadfin abundance and climatic oscillations in Chang-Yuen Ridge, Taiwan; the insights are valuable for fishery management amidst changing climate conditions.

Bangana devdevi, a Native Carp of the Himalayan Biodiversity Hotspot: Reproductive Biology and Hormonal Breeding Efforts for Conservation and Aquaculture Promotion

Efficient conservation efforts for valued fish species such as Bangana devdevi, a medium‐sized minor carp prevalent in Southeast Asian countries, can be facilitated through well‐established artificial breeding techniques. This study aimed to investigate the reproductive biology of B. devdevi and focused on optimizing hormone dosages for breeding purposes for the first time. The research findings indicated that the highest gonadosomatic index (GSI) for males (1.17) was observed in August, while for females, it peaked in July (2.24). Female fish exhibited absolute fecundity ranging from 2089 to 26287 eggs, corresponding to body weights ranging between 10.46 and 153.73 g. The relative fecundity ranged from 170 to 298 eggs g−1 of body weight. To induce breeding, female brooders were administered Gonopro‐FH hormone through three experimental groups: G‐FH_0.4, G‐FH_0.5, and G‐FH_0.6, with doses of 0.4 mL, 0.5 mL, and 0.6 mL·kg−1 of body weight, respectively. Spawning occurred within 6–10 h after hormone administration. Among these groups, G‐FH_0.5 exhibited the highest fertilization rate (94.25%) and hatching rate (89.03%), significantly surpassing the rates observed in G‐FH_0.4 and G‐FH_0.6 (p &lt; 0.05). This study provided valuable insights into the reproductive biology of B. devdevi and emphasized its potential application in developing management and conservation strategies for this species in rivers and tributaries. Furthermore, the knowledge gained from induced breeding holds promise for future large‐scale seed production initiatives.

Гидробиоценозы озера Малое Янисъярви (Южная Карелия) в условиях товарного выращивания форели

Based on our own and literature data, the state of the ecosystem of Lake Maloe Yanisjarvi (South Karelia) in the conditions of industrial trout farming (since 2020) has been analyzed. The reservoir belongs to the mineralized (24.4-31.6 mg/l), calcium sulfate class. The chemical composition of the waters is not subject to significant fluctuations throughout the year. Among the forms of mineral nitrogen, nitrate and ammonium predominate (the maximum concentration noted is 0.12 mg/l). The total phosphorus content does not exceed 0.012 mg/l, mineral – 0.01 mg/l. Fluctuations in the concentration of dissolved oxygen are in the range of 7.0-9.1 mg/l. High flow rate (indicator of conditional water exchange 3.5 year-1) is the main stabilizing factor contributing to the preservation of the hydrochemical regime of the reservoir. In general, the water masses of Lake Maloe Yanisjarvi in their chemical composition meet the requirements for the aquatic environment in the cage cultivation of salmon. The data on the main hydrological and hydrobiological indicators of the lake are presented. According to the level of quantitative development of zooplankton in the summer-autumn period, the lake corresponds to the oligotrophic type with a biomass of up to 1 g/m3, benthos – to the α-mesotrophic type (2.8 g/m2). The reservoir belongs to the highest fishery category, according to literature data, valuable fish species (salmon, trout, whitefish and grouse) are noted as part of the ichthyofauna. Recommendations on the timing of the ecological expertise of the lake are given.

Амурский чебачок Pseudorasbora parva (Cyprinidae) в водоемах и водотоках Дагестана

Information is provided on the distribution of a species alien to the ichthyofauna of Dagestan – the Amur Top-mouth gudgeon Pseudorasbora parva (Temminck et Schlegel, 1846) within the region. It was found that the species expanded its range in the region under consideration, in 2021 it was found in the rivers Manasozen (9 copies), Gamriozen (10 copies), Ulluchai (6 copies), Rubas (6 copies), Avar koisu (a tributary of the Sulak River, in the area of the Gotsatli HPP), as well as in L. Mooch. It is assumed that the widespread distribution of P. parva is associated with high ecological plasticity, migration activity of larvae and fry, their high survival rate, rapid growth and accelerated puberty. The presented morphological variability of the Amur Topmouth gudgeon population based on the study of 20 signs, including 5 meristic and 15 plastic, revealed a slight variability of morphological signs due to different habitat conditions in the region. The Amur Topmouth gudgeon is a natural focus of an infectious disease of the swim bladder, dangerous for autochthonous ichthyofauna and aquaculture facilities, and a food competitor and consumer of caviar and larvae of autochthonous fish. With high numbers and prolonged starvation, P. parva can be a serious competitor for juvenile carp and variegated carp, and exhibit a predatory reaction towards commensurate juveniles of commercially valuable fish species. To control the number of this alien in the region, it is advisable to use native predators – perch Perca fluviatilis (Linnaeus, 1758), pike Esox lucius (Linnaeus, 1758) and walleye Sander lucioperca (Linnaeus, 1758).

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води