Background.The selection of optimal feed formulations is a primary factor determining the efficiency and sustainability of aquaculture. The Australian Red Claw Crayfish,Cherax quadricarinatus(von Martens, 1868), known for its high growth rates and tolerance to water quality parameters, is a popular aquaculture species worldwide. However, the development of specialized feeds for this species remains insufficiently addressed. In practice, prepared feeds for other crustaceans or for sturgeon are commonly used for its cultivation. In natural habitats, the diet of this crayfish consists primarily of macrophytes (up to 87.5%) and detritus (42.8%), with the proportion of the plant component increasing with body size. The omnivorous feeding type creates opportunities for finding cheaper protein sources compared to fishmeal. Analysis of scientific research has shown that black soldier fly larvae and yellow mealworm can be used as alternatives to fishmeal in feeds for the Australian crayfish. Among plant-based raw materials, soybean, rapeseed, and peanut meal are unsuitable components. The specific feeding behavior of the Red Claw Crayfish necessitates sufficient stabilization and binding of feed pellets. Furthermore, the shape of the feed pellets must be considered, with the prism shape being the most preferable. Developing feed formulations that account for the biological specifics of the Red Claw Crayfish will enhance the efficiency of its aquaculture and reduce costs for farmers. Purpose.To identify the main dietary characteristics and nutritional requirements of the Australian red claw crayfishCherax quadricarinatusin order to develop feed formulations that ensure high farming efficiency and economic sustainability in aquaculture. Materials and methods.A comparative – analytical approach was applied in this study. The information base was formed through the analysis of more than 150 scientific publications from both domestic and international sources. Literature searches were conducted in databases such as eLibrary, ScienceDirect, ResearchGate, Google Scholar, Wiley, and others, using keywords in both Russian and English. Results.The analysis revealed thatCherax quadricarinatusis capable of effectively digesting both plant- and animal-based dietary components. Protein was identified as the primary limiting nutrient, with an optimal content for juveniles ranging between 30-33%. As an alternative to fish meal – the most expensive component of aquafeeds – promising protein sources include black soldier fly larvae, yellow mealworms, poultry by-products, and microbial protein DREAMFEED. The species’ specific feeding behavior necessitates high water stability and mechanical strength of feed pellets, as well as adjustment of their shape and size according to crayfish age; prismatic pellets are considered optimal. Experimental studies of both domestic and international feed formulations demonstrated that the use of alternative protein sources and locally available raw materials can reduce feed costs without compromising growth rates or survival. Conclusion.The efficiency ofCherax quadricarinatusaquaculture is largely determined by the quality and nutritional balance of the feed. The biological features of this species, including its versatile digestive system and ability to process a wide range of organic substances, provide a basis for the development of diets using alternative protein sources. Diets that maintain an optimal balance of proteins, lipids, carbohydrates, vitamins, and minerals contribute to enhanced productivity, survival, and profitability of aquaculture farms. The improvement of feed formulations and manufacturing technologies aimed at increasing water stability and adapting pellet size to different developmental stages represents a key direction for the further advancement ofCherax quadricarinatusaquaculture.

Background.The study is devoted to the study of the main fish-breeding and biological characteristics (growth rates, survival, etc.) of juvenile Australian red-clawed crayfishCherax quadricarinatus(von Martens, 1868) when kept in different temperature conditions. In the experiment, two temperature zones were compared: 22 °C (suboptimal conditions for commercial cultivation) and 26 °C (optimal conditions). The results showed that at a temperature of 22 °C, there was a higher increase in weight (18.03%) and length (4.19%) compared to suboptimal conditions (5.99% and 4.92%, respectively). The Fulton fatness ratio decreased in both groups. The data obtained is important for commercial aquaculture for the correct development of cultivation biotechnologies. Purpose.The aim of the work was to study the main fish-breeding, biological and physiological parameters of juvenileC. quadricarinatuswhen they are kept in different temperature conditions. Materials and methods.The study was conducted on 73-day-oldC. quadricarinatusindividuals (n=40), divided into 2 groups of 20 specimens each. in each. Group No. 1 was kept at a temperature of 22-23°C, group No. 2 – at 26-27°C. The specimens were placed in polypropylene containers with overall dimensions of 74x57x41 cm. Each tank had an individual recycled water filtration system. To reduce cannibalism, PVC pipe shelters were placed in the tank. The duration of the experiment was 28 days. The main water parameters were monitored daily using specialized equipment and sets of test systems. Feeding was carried out twice a day: frozen chironomid larvae (50%) and young bean fruits (50%) in the amount of 6% of the biomass. The body weight and length of each individual were measured every 7 days of the experiment. Based on the data obtained, the main fish-breeding and biological indicators (Fulton fatness coefficient, specific growth rate, survival rate) were calculated. Amino acid analysis was performed by capillary electrophoresis after acid/alkaline hydrolysis of muscle tissue. To minimize errors, averaged samples from individuals of different sizes were used. Results.During the study, the hydrochemical regime corresponded to the optimal values for the content of C. quadricarinatus. The absence of toxic nitrogen compounds, as well as copper ions, made it possible to create the necessary conditions for the experiment. In group No. 1, the water temperature averaged 22.26 °C, and in group No. 2 – 26.96 °C. The concentration of dissolved oxygen (O2) during the experiment averaged 7.52 mg/l and 7.87 mg/l, respectively. As a result of the research, it was found that in group No. 1, the body weight of juveniles increased by 5.99%, length – by 4.92%, while the Fulton fatness coefficient decreased by 8.18%. In group No. 2, weight gain was more pronounced (18.03%), with a moderate increase in length (4.19%) and a smaller decrease in fatness ratio (4.1%). The analysis of the amino acid composition of muscle tissue revealed significant differences between the studied groups. The concentration of arginine in the muscles of juvenile crayfish from group 1 was significantly higher than in group 2. The total concentrations of glutamic acid and glutamine were also higher under suboptimal conditions. These changes most likely indicate metabolic adaptation to stressful conditions, especially at temperatures close to the lower optimal limit of the species. Thus, during the experiment, it was found that the water temperature of 26-27 °C contributes to higher growth rates and survival of juveniles, while 22-23 ° C causes changes in the physiological status ofC. quadricarinatus. Conclusion.The study revealed differences in the fish-biological and physiological parameters ofC. quadricarinatusjuveniles kept in different temperature conditions. At an average temperature of 26.96°C, the maximum increase in weight (18.03%) and body length (4.19%) was observed, while at 22.26°C these indicators were significantly lower (5.99% and 4.92%, respectively). Although the survival rate remained high (95-100%) in both cases, a decrease in the fatness coefficient by 8.18% at a lower temperature indicates the stress effect of this factor on the aquatic organisms. Amino acid analysis showed an increased content of arginine (5.315%) and glutamic acid (4.221%) in individuals kept at a temperature of 22-23 ° C, which indicates the activation of compensatory metabolic mechanisms. These data probably indicate the high possible adaptability of the species in question to changing environmental conditions. The results obtained are of great practical importance for the further development of crustacean aquaculture (astaculture) in the climatic conditions of the Russian Federation.

Background.This review systematizes current scientific data on the influence of abiotic (pH, temperature, hypoxia, ammonia, nitrite) and biotic (viral and bacterial infections) stress factors on gene expression in crustaceans of the orderDecapoda. Molecular responses affecting key functional groups of genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism, and cellular homeostasis are analyzed. Stress-induced changes in gene expression are complex, tissue-specific, and time-dependent, representing key adaptive mechanisms. The results of this analysis have important practical implications for aquaculture, opening up prospects for identifying molecular markers of stress resistance and developing strategies for optimizing the maintenance conditions of commercially important species. Purpose.This review aims to systematize and analyze current scientific data on the influence of abiotic (such as pH, temperature, hypoxia, ammonia, nitrites) and biotic (viral and bacterial infections) stress factors on expression of genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism and cellular homeostasis in crustaceans of the orderDecapoda. Materials and methods.The research was conducted in the scientific research laboratory “Center of Agrobiotechnology” of the Don State Technical University in 2024-2025. Results.Complex changes in the expression of key genes regulating immunity, osmoregulation, antioxidant protection, chitin metabolism, and cellular homeostasis have been identified. It has been shown that these tissue-specific and time-dependent changes in expression are the central mechanism of the adaptive response to stress. Conclusion.An analysis of current scientific data has allowed us to systematize information on the influence of abiotic and biotic stress factors on gene expression in crustaceans, particularly in members of the orderDecapoda. It has been established that changes in key environmental parameters (such as temperature, pH, ammonia and nitrite concentrations) and exposure to pathogens (viruses, bacteria) trigger complex molecular responses affecting genes associated with immunity, osmoregulation, antioxidant defense, chitin metabolism, and cellular homeostasis.

In the context of the global decline in natural populations of sturgeon fish and increased requirements for the environmental safety of aquaculture, the search for alternatives to antibiotics is of particular importance. The use of bacteriocins, particularly nisin, a natural antimicrobial peptide that is approved for use in the food industry, is a promising approach. The aim of this study is to comprehensively evaluate the impact of the bacteriocin nisin on the growth and survival of one-year-old sterlet (Acipenser ruthenus Linnaeus, 1758), a valuable species in modern sturgeon farming. The experiment was conducted in a laboratory aquaculture facility using two groups of fish. The control group received a basic diet, while the experimental group received a diet with 0.1% nisin added. Hydrochemical parameters of the water were monitored for 28 days to ensure optimal conditions. Morphometric indicators and survival rates of the hydrobionts were analyzed to assess the effectiveness of the supplement. The results of the study showed a statistically significant positive effect of the lowland on the production qualities of sterlet. In the experimental group, the average individual weight increased by 19.14%, and the total body length increased by 7% compared to the control group. The absolute increase in weight in the experimental group was 25.20 g, compared to 18.80 g in the control group. The most significant effect of the lowland was the increase in the survival rate of the young fish to 76%, which was 28% higher than in the control group (48%). The data obtained demonstrate that the inclusion of nisin in compound feed not only stimulates growth, but also significantly increases the survival rate of young sterlet. The results of the work confirm the prospects of using nisin as an effective and safe feed additive in industrial sturgeon farming, which minimizes the risks associated with the use of traditional antibiotics.