Research on the Impact of Ecological Circulating Freshwater Aquaculture Models on Fish Quality Improvement

Research on the Impact of Ecological Circulating Freshwater Aquaculture Models on Fish Quality Improvement

The "14th Five-Year Plan for National Fishery Development" clearly calls for "promoting the green development of aquaculture and accelerating the construction of a modern aquaculture system." Against this background, the ecological circulating freshwater aquaculture model has emerged. This model establishes a relatively closed artificial ecosystem by simulating the material circulation and energy flow of natural ecosystems. Compared with traditional aquaculture models, ecological circulating aquaculture has significant advantages in environmental regulation, feed utilization, and disease prevention and control. It not only effectively reduces environmental pollution but also significantly improves fish quality.

1 Basic Principles and Technical System of Ecological Circulating Freshwater Aquaculture Model

1.1 Basic Principles of Ecological Circulating Aquaculture

The ecological circulating aquaculture model is based on the principles of material circulation and energy flow in ecosystems, constructing a relatively closed artificial ecosystem. In this system, the cultivation unit, purification unit, and biological transformation unit are closely connected through water circulation, forming a complete material circulation chain. Organic waste generated during the cultivation process is transformed into inorganic nutrients through biodegradation, which are then absorbed and transformed by microorganisms and aquatic plants, ultimately achieving water purification and resource recycling.

1.2 Key Technical Support Systems

The successful operation of the ecological circulating aquaculture model depends on the synergistic effect of multiple key technologies. Among them, biological filtration technology achieves effective nitrogen removal from Aquaculture Water by using nitrifying bacteria to convert ammonia nitrogen into nitrite and then into nitrate, while denitrification reduces nitrate to nitrogen gas. Biofilm methods and biological filters, as the two most commonly used biological filtration methods, can significantly reduce organic pollutant content in the water. Physical filtration systems use mechanical filtration, foam separation, and sedimentation processes to remove suspended solids and particulate matter from the water. The application of microscreen filters and drum filters effectively improves filtration efficiency and maintains water quality stability.

1.3 Equipment and Facility Requirements

Ecological circulating aquaculture systems require comprehensive equipment and facilities. The cultivation unit uses high-density culture tanks, circular tanks, or raceway tanks, equipped with aeration equipment and automatic feeding systems to achieve intensive cultivation. The purification treatment unit includes sedimentation tanks, biological filters, plant purification tanks, etc., equipped with necessary pumps and piping systems to ensure smooth water circulation. The monitoring and control unit uses online monitoring instruments for dissolved oxygen, pH, temperature, etc., equipped with automatic control systems to achieve precise regulation of the cultivation environment.

2 Mechanisms of Fish Quality Improvement in Ecological Circulating Aquaculture Model

2.1 Impact of Water Quality Environment Optimization on Fish Quality

The ecological circulating aquaculture model creates a stable growth environment for fish through continuous water purification and regulation. The system maintains high dissolved oxygen levels (6–8 mg/L) through advanced aeration equipment and precise control systems. This optimized dissolved oxygen environment significantly promotes fish metabolism, improves feed conversion efficiency, not only significantly increases the protein content of fish meat but also makes muscle tissue firmer. At the same time, through intelligent temperature control systems that precisely maintain water temperature within the optimal range, this stable temperature environment effectively increases fish growth rate and significantly improves muscle fiber development, thereby comprehensively enhancing meat quality. Additionally, the system maintains an appropriate pH range through automatic adjustment devices. This stable pH environment effectively reduces fish stress responses, promotes digestion, absorption, growth, and development, ultimately significantly improving the tenderness of fish meat.

2.2 Impact of Improved Feed Utilization Efficiency on Quality

In the ecological circulating aquaculture model, feed utilization efficiency is significantly improved through scientifically optimized feed formulations and precise feeding strategies. In terms of feed nutritional balance, the system reasonably adjusts the proportions of protein, fat, and carbohydrates according to the physiological needs of different fish species, while adding essential trace elements such as iron, zinc, selenium, and vitamins A, D, E, and comprehensively improves feed quality through the addition of functional additives such as probiotics and enzyme preparations. In terms of precise feeding management, the system establishes a complete feeding program. Through intelligent feeding management systems, the feeding amount is dynamically adjusted according to the nutritional needs of fish at different growth stages. Automatic feeding systems precisely control daily feeding frequency and timing, and through real-time monitoring of fish feeding behavior and growth status, feeding strategies are adjusted promptly to ensure scientific and precise feeding, maximizing feed conversion rate and reducing cultivation costs.

2.3 Impact of Disease Prevention and Control System on Quality

The ecological circulating aquaculture model establishes a comprehensive disease prevention and control system, ensuring fish health through a "prevention first, combining prevention and treatment" approach. In terms of prevention, the system regularly performs ultraviolet disinfection and chemical disinfection of culture tanks, equipment, and tools, effectively reducing the number of pathogenic microorganisms. At the same time, through the addition of immune enhancers and nutritional supplements, fish resistance is improved, and water quality stability is maintained through precise environmental regulation systems, reducing stress responses. In terms of biological control, the system establishes a healthy aquatic microecosystem by introducing beneficial microbial groups such as photosynthetic bacteria and lactic acid bacteria. These beneficial microbial groups not only decompose organic matter but also effectively inhibit the reproduction of pathogenic bacteria through competitive and antagonistic effects. The active substances they produce also promote the development of the fish digestive system and enhance their immunity.

3 Practical Application and Effect Analysis of Ecological Circulating Aquaculture Model

3.1 Case Studies of Typical Aquaculture Models

3.1.1 Multi-Stage Biological Filter Circulation System

The multi-stage biological filter circulation system adopts an innovative three-stage biological filter series treatment process. Different functional microbial groups such as nitrifying bacteria, heterotrophic bacteria, and photosynthetic bacteria are cultivated in each stage of the filter. Through the synergistic effect of these functional microbial groups, stepwise degradation and transformation of ammonia nitrogen, nitrite, and organic matter are achieved. The first-stage filter primarily degrades organic matter, the second-stage filter handles ammonia nitrogen conversion, and the third-stage filter completes final water purification. This stepwise treatment model improves the overall system treatment efficiency by 30%–50%, not only significantly improving water quality but also reducing water exchange volume and lowering operating costs.

3.1.2 Ecological Pond–Recirculating Water Composite System

The ecological pond–recirculating water composite system innovatively combines industrial recirculating aquaculture technology with traditional ecological pond aquaculture models, fully leveraging the advantages of both models. The industrial recirculating system provides precise environmental control and efficient Water Treatment capacity, while the ecological pond achieves natural purification of aquaculture wastewater through the synergistic effects of aquatic plants and microorganisms. This composite aquaculture model not only increases stocking density by 2–3 times, achieving intensive production, but more importantly, maintains stable water quality through dual purification effects, providing an optimal environment for fish growth and significantly improving output efficiency per unit area.

3.1.3 Three-Dimensional Ecological Aquaculture System

The three-dimensional ecological aquaculture system adopts an innovative multi-species three-dimensional aquaculture model. By scientifically and rationally configuring aquatic organisms at different nutritional levels, such as filter-feeding fish in the surface layer, plankton-feeding fish in the middle layer, and detritus-feeding fish in the bottom layer, a complete ecological food chain is formed. This ecological niche complementary aquaculture model not only improves water space utilization but, more importantly, establishes natural ecological balance through predator-prey relationships between different organisms, enhancing the system's self-purification capacity, making the culture environment more stable, and effectively reducing disease incidence and environmental pollution risks.

3.2 Quality Improvement Effect Evaluation

3.2.1 Meat Quality Indicator Improvement

In terms of meat quality indicator improvement, the ecological circulating aquaculture model significantly enhances the quality of fish products. Through optimized water quality environment and scientific feeding management, the muscle protein content of cultured fish increases by 5%–8% compared to traditional aquaculture, while muscle fiber arrangement becomes more regular and compact. This improvement directly enhances the tissue structure of fish meat. The significant improvement in meat tenderness is mainly reflected in a more delicate texture, with muscle fibers separating more easily during chewing. Additionally, due to the improved culture environment and increased feed utilization efficiency, the flavor of fish meat is also significantly enhanced, with a richer umami taste and better mouthfeel, greatly improving the market competitiveness of the product.

3.2.2 Growth Performance Improvement

In terms of growth performance, the ecological circulating aquaculture model achieves significant improvement effects. The optimized culture environment and scientific feeding management increase fish growth rate by 15%–20% compared to traditional aquaculture, significantly shortening the culture cycle. Feed conversion rate increases by 10%–15%, greatly reducing cultivation costs. Meanwhile, due to the more stable environment and reduced disease incidence, survival rate increases by 8%–12%. Particularly noteworthy is that through precise feeding management and environmental regulation, the uniformity of cultured fish size is significantly improved, reducing the labor intensity of grading and screening, improving cultivation efficiency, and laying the foundation for large-scale production.

3.3 Economic Benefit Analysis

In terms of economic benefits, the ecological circulating aquaculture model demonstrates significant advantages. Benefiting from efficient water quality purification systems and scientific feeding management, yield per unit culture area increases by 30%–40% compared to traditional aquaculture, significantly improving land use efficiency. Through optimized feed formulations and precise feeding strategies, feed costs are reduced by 20%–25%, greatly reducing production input. Due to stable culture environment and comprehensive disease prevention and control systems, drug usage is reduced by 60%–70%, not only lowering production costs but also improving the food safety of products.

4 Existing Problems and Optimization Directions

4.1 Technical Problems

In terms of technical application, the ecological circulating aquaculture model still faces some urgent problems. Due to the need for comprehensive water treatment systems, monitoring equipment, and intelligent control devices, initial investment costs are relatively high, which limits its promotion and application to some extent. The daily operation and management of the system require specialized technical personnel and refined management measures, placing higher demands on the technical level and management capabilities of farmers. Many core equipment items, such as precision filters and intelligent control systems, still rely on imports, which not only increases construction and maintenance costs but also poses challenges to technological innovation. Additionally, the treatment efficiency of biological filtration systems still has room for improvement, particularly under high-density culture conditions, where further optimization of microbial community structure and enhanced treatment capacity are needed.

4.2 Management Problems

At the management level, the ecological circulating aquaculture model still has several key problems that need to be addressed. There is a general lack of professional technical personnel in frontline aquaculture who understand both biological technology and equipment operation, which severely constrains the improvement of cultivation efficiency. Due to significant differences in culture conditions and management levels across regions, the standardization of systems is insufficient, making it difficult to establish unified technical specifications and management standards. Meanwhile, during system operation, maintaining stable water quality environment and precise control parameters makes operating cost control more difficult. Additionally, the risk prevention and control system for emergencies and system failures is not yet fully developed, requiring further establishment and improvement of emergency plans and safeguard mechanisms.

4.3 Optimization Directions

In response to the problems existing in the development of the ecological circulating aquaculture model, future optimization directions should focus on the following aspects: actively promote localized research and manufacturing of aquaculture equipment to reduce system construction and maintenance costs; strengthen the cultivation of professional technical personnel through school-enterprise cooperation and other means to improve the professional level of frontline aquaculture personnel; establish a comprehensive standardized management system, formulate unified technical specifications and operating standards, and improve the standardization level of the cultivation process; at the same time, strengthen the research and application of intelligent monitoring systems, achieve precise management and remote monitoring of the cultivation process through Internet of Things and big data technology, and further improve cultivation efficiency and management level.

5 Conclusion

The ecological circulating freshwater aquaculture model has achieved significant results in improving fish quality through the construction of a complete ecosystem and precise environmental regulation. However, in the process of promotion and application, this model still faces challenges such as high initial investment costs, high technical barriers, and insufficient standardization. Future efforts should focus on strengthening localized equipment research and development, professional talent cultivation, and standard system construction. Through technological innovation and management optimization, system operation efficiency and economic benefits should be continuously improved. This is not only crucial for the sustainable development of aquaculture enterprises but also an important pathway for promoting the transformation and upgrading of China's aquaculture industry.