Detailed Q&A on Controllable Ecological Eel Farming Technology
Q&A on Controllable Ecological Eel Farming Technology
Conventional intensive eel farming relies on large amounts of water exchange and medication to prevent and treat diseases, which severely restricts the survival and development of the eel industry. Controllable ecological eel farming technology not only saves water and energy, but also reduces or eliminates the use of medication. It is a feasible new eel farming technology.
□Text by Yuan Chonggui, College of Biological Science and Engineering, Fuzhou University; Guan Jingxiang, National Fisheries Technology Extension Center
1. What is controllable ecological eel farming?
Answer: When people talk about "ecological farming," most understand it as a simple, natural, extensive, low-yield, and low-efficiency farming method. However, when the word "controllable" is added, the above understanding is completely wrong. Controllable ecological farming is an intensive, high-efficiency precision farming model with the characteristics of being "healthy and safe, economical and practical, energy-saving and emission-reducing, and highly efficient and environmentally friendly."
"Controllable ecological eel farming" is a relatively complex ecological system engineering project. In plain terms, it means consciously modifying existing eel farming facilities to regulate and create as much as possible a good ecological environment more suitable for the growth and development of eels: using the principle of biological mutual inhibition to effectively prevent the occurrence of pests and diseases, and reduce or eliminate the use of medication; reducing the impact of climate change on eel farming through temperature control and insulation, greatly shortening the growth cycle and improving feed efficiency; saving large amounts of energy and reducing production costs by reducing or even eliminating water exchange; enhancing the vitality of the aquatic ecosystem through moderate lighting and aeration; controlling biological digestion balance and maintaining the self-purification capacity of the micro-ecosystem through physical treatment of eel feces. Through these measures, the aquatic ecosystem is made to surpass nature and efficiently produce healthy, safe, and high-quality eels according to our wishes.
2. Why does controllable ecological farming require insulation?
Answer: Eels are poikilothermic animals, and their growth and metabolic efficiency depend on the temperature of the farming water. When the temperature is suitable (around 25°C for European eels and around 27°C for Japanese eels), their internal metabolism is vigorous, the efficiency of food digestion and absorption is highest, and growth speed is fastest. If the temperature is too high or too low, the digestion and absorption of food by eels is affected, and growth is relatively slower. In eel farming, building greenhouses and installing heating and temperature control systems to maintain the optimal growth temperature for eels not only benefits eel growth but also benefits the reproduction of various plankton and microorganisms such as bacteria, maintaining the micro-ecological balance in the water body. At the same time, building greenhouses allows appropriate lighting to meet the growth needs of photosynthetic phytoplankton in the water body, effectively consuming nutrients in the water and purifying water quality; greenhouses also help reduce heat loss, keeping water temperature relatively constant, so that eel farming is basically unaffected by seasonal and climate changes.
3. Why does controllable ecological farming require the installation of an aeration system?
Answer: Controllable ecological farming differs from traditional factory farming in that the farming water body contains large amounts of zooplankton, phytoplankton, and decomposing microorganisms. On cloudy days and at night, especially in the latter half of the night, all organisms in the farming water body reduce or stop photosynthesis, while the oxygen consumption of respiration increases greatly, which may cause short-term oxygen deficiency in the water body and pose a threat to eel health. This is the bottleneck problem of controllable ecological farming. If dissolved oxygen in the water is not increased at this time, eels are most likely to die from floating-head oxygen deficiency, and water quality may deteriorate sharply. Therefore, it is necessary to install aeration facilities in eel farming ponds to promptly increase dissolved oxygen in the farming water body and break through the bottleneck of possible short-term oxygen deficiency each day. Strengthening aeration can also effectively maintain the high digestive capacity of microorganisms in the water, greatly increase the eel farming density in the water body, thereby achieving relatively high yield per unit area and improving production efficiency.
4. Why should controllable ecological farming avoid large amounts of water exchange?
Answer: "Large amounts of water exchange" is almost the "patent" of China's factory-based intensive aquaculture model. Due to high farming density, water quality easily deteriorates, and large amounts of water exchange are unavoidable, often with daily water exchange reaching several times or even more than ten times the volume. Such large water exchange farming results in very few plankton and decomposing microorganisms in the water body. As the saying goes, "When the water is too clear, there are no fish." Fish living long-term in clear water are similar to humans living in a desert without vegetation or wetlands; the living environment is extremely harsh. The harms of clear-water fish farming caused by large water exchange are many, such as:
A. The feces excreted by fish in the farming water body cannot be decomposed in time due to the lack of plankton and decomposing microorganisms, and thus accumulate in large amounts;
B. Dissolved oxygen in the water body is continuously consumed by the respiration of farmed organisms, while at the same time lacking supplementation from photosynthesis, which easily leads to a rapid decrease in dissolved oxygen in the water;
C. Harmful pathogens such as Saprolegnia and common eel parasites (such as Ichthyophthirius, Dactylogyrus, Trichodina, etc.) are most likely to reproduce in large numbers in this monotonous clear-water system before algae and other photosynthetic plankton and zooplankton, easily causing explosive fish diseases;
D. Frequent water exchange during farming not only wastes water resources, but each new batch of water is a new environment for the fish, causing the fish to be frequently in a state of conditional stress, seriously affecting their feeding and growth;
E. Large amounts of water exchange make it difficult to keep the farming water temperature constant, not only causing stress to fish but also increasing heating energy consumption and raising production costs;
F. Frequent water exchange often brings pathogenic bacteria, viruses, and parasites through the water source, greatly increasing the probability of fish disease;
G. Fish have no sense of security in clear water and are easily stressed by the environment, and their feeding efficiency is also greatly reduced as a result.
Counting these drawbacks of large water exchange, it is not difficult to understand why the controllable ecological farming model does not adopt large water exchange. Controllable ecological farming emphasizes what people often say: "To raise fish, first raise the water." The so-called "raising water" means reducing water exchange as much as possible or even not exchanging water during the farming process, and intentionally cultivating large amounts of phytoplankton, zooplankton, and decomposing microorganisms in the farming water body, so that the water body forms an ecosystem with biodiversity, allowing various microorganisms to efficiently digest fish feces and other harmful substances in the water, purify water quality, and create a balanced and stable good ecological environment for fish, effectively avoiding the various drawbacks caused by clear-water fish farming.
5. Why can't water disinfectants and other medications be used in controllable ecological farming?
Answer: One of the most important aspects of controllable ecological farming technology is cultivating large amounts of zooplankton, phytoplankton, and decomposing microorganisms in the farming water body. Sometimes "probiotics" are also added to the farming water body. The purpose is to achieve water quality self-purification through the water body's ecosystem, while inhibiting outbreaks of harmful pathogens and parasites, and protecting fish safety. If water disinfectants, antibiotics, or insecticides are used during farming, various microorganisms will die in large numbers, and the carefully established water body ecosystem will be damaged or even collapse. When the aquatic ecosystem is out of balance, harmful pathogens and parasites in the water always take the lead and reproduce in large numbers, subsequently causing pests and diseases. Abuse of medication will fall into a vicious cycle of "medication - water exchange - disease - medication." Fish often develop various drug-induced diseases, and there may be a risk of excessive drug residues in fish. Controllable ecological farming requires a stable, diverse biological system, and the use of any medication may damage this system or even cause serious consequences.
6. Why does feed formula affect controllable ecological farming?
Answer: In a controllable ecological farming system, the digestive capacity of microorganisms and the amount of fish feces discharged are in a dynamic balance. Excessive feces discharge will cause micro-ecological imbalance and produce adverse effects. Whether the feed formula is reasonable directly affects the feed digestion and absorption rate and the nutrient content in fish feces. Long-term intake of feed with an unreasonable nutritional formula by eels will cause poor health, which in turn affects feed digestion and absorption rate, increases the burden on the ecosystem, and reduces the fish body's resistance to disease. In addition, if antibiotics are added to eel feed, they will kill beneficial bacteria in the eel intestinal tract and also affect the eel's digestion and absorption capacity. Choosing a good feed formula helps improve its digestion and absorption rate. Adding fermented soybean meal or other active fermentation products to the feed formula is very beneficial for cultivating beneficial bacteria in the eel intestinal tract and helping eels digest and absorb.
7. Why does controllable ecological farming require reasonable density?
Answer: In a controllable ecological farming system, fish feces mainly rely on microorganisms in the water for timely digestion, and the water body ecosystem's capacity to digest fish feces has a limit. If the farming density is too high, the feces produced may exceed the digestive capacity of the ecosystem, the ecological balance will be broken, and water quality will deteriorate. To avoid this situation, controlling appropriate farming density is crucial. Preliminary experiments show that under conditions of no water exchange, no sewage discharge, and relatively constant temperature, a juvenile eel rearing density of 500-800 fish/m2 is feasible; for adult eel farming under conditions of no water exchange and no sewage discharge, the stocking density can reach 6-8 kg/m2.
8. How can the controllable ecological farming model achieve higher-density farming?
Answer: In the controllable ecological farming model, the key to achieving higher-density farming is how to break through the digestive limit of the water body ecosystem for feces. This is also the issue readers care about most. We know that the digestive limit of microorganisms cannot be broken through. The only solution is to use physical methods to separate part of the fish feces from the water body, reduce the burden on microorganisms, and achieve balance under human control. This is a key link in controllable ecological farming. There are many specific separation methods, commonly used ones such as micro-particle filtration, constructed wetland filtration, and cyclone foaming separation. The higher the efficiency of manually separating fish feces, the higher the stocking density that can be achieved.
--------------------------------------
:guzhang::guzhang:
--------------------------------------
Eel rice is delicious
□Text by Yuan Chonggui, College of Biological Science and Engineering, Fuzhou University; Guan Jingxiang, National Fisheries Technology Extension Center
1. What is controllable ecological eel farming?
Answer: When people talk about "ecological farming," most understand it as a simple, natural, extensive, low-yield, and low-efficiency farming method. However, when the word "controllable" is added, the above understanding is completely wrong. Controllable ecological farming is an intensive, high-efficiency precision farming model with the characteristics of being "healthy and safe, economical and practical, energy-saving and emission-reducing, and highly efficient and environmentally friendly."
"Controllable ecological eel farming" is a relatively complex ecological system engineering project. In plain terms, it means consciously modifying existing eel farming facilities to regulate and create as much as possible a good ecological environment more suitable for the growth and development of eels: using the principle of biological mutual inhibition to effectively prevent the occurrence of pests and diseases, and reduce or eliminate the use of medication; reducing the impact of climate change on eel farming through temperature control and insulation, greatly shortening the growth cycle and improving feed efficiency; saving large amounts of energy and reducing production costs by reducing or even eliminating water exchange; enhancing the vitality of the aquatic ecosystem through moderate lighting and aeration; controlling biological digestion balance and maintaining the self-purification capacity of the micro-ecosystem through physical treatment of eel feces. Through these measures, the aquatic ecosystem is made to surpass nature and efficiently produce healthy, safe, and high-quality eels according to our wishes.
2. Why does controllable ecological farming require insulation?
Answer: Eels are poikilothermic animals, and their growth and metabolic efficiency depend on the temperature of the farming water. When the temperature is suitable (around 25°C for European eels and around 27°C for Japanese eels), their internal metabolism is vigorous, the efficiency of food digestion and absorption is highest, and growth speed is fastest. If the temperature is too high or too low, the digestion and absorption of food by eels is affected, and growth is relatively slower. In eel farming, building greenhouses and installing heating and temperature control systems to maintain the optimal growth temperature for eels not only benefits eel growth but also benefits the reproduction of various plankton and microorganisms such as bacteria, maintaining the micro-ecological balance in the water body. At the same time, building greenhouses allows appropriate lighting to meet the growth needs of photosynthetic phytoplankton in the water body, effectively consuming nutrients in the water and purifying water quality; greenhouses also help reduce heat loss, keeping water temperature relatively constant, so that eel farming is basically unaffected by seasonal and climate changes.
3. Why does controllable ecological farming require the installation of an aeration system?
Answer: Controllable ecological farming differs from traditional factory farming in that the farming water body contains large amounts of zooplankton, phytoplankton, and decomposing microorganisms. On cloudy days and at night, especially in the latter half of the night, all organisms in the farming water body reduce or stop photosynthesis, while the oxygen consumption of respiration increases greatly, which may cause short-term oxygen deficiency in the water body and pose a threat to eel health. This is the bottleneck problem of controllable ecological farming. If dissolved oxygen in the water is not increased at this time, eels are most likely to die from floating-head oxygen deficiency, and water quality may deteriorate sharply. Therefore, it is necessary to install aeration facilities in eel farming ponds to promptly increase dissolved oxygen in the farming water body and break through the bottleneck of possible short-term oxygen deficiency each day. Strengthening aeration can also effectively maintain the high digestive capacity of microorganisms in the water, greatly increase the eel farming density in the water body, thereby achieving relatively high yield per unit area and improving production efficiency.
4. Why should controllable ecological farming avoid large amounts of water exchange?
Answer: "Large amounts of water exchange" is almost the "patent" of China's factory-based intensive aquaculture model. Due to high farming density, water quality easily deteriorates, and large amounts of water exchange are unavoidable, often with daily water exchange reaching several times or even more than ten times the volume. Such large water exchange farming results in very few plankton and decomposing microorganisms in the water body. As the saying goes, "When the water is too clear, there are no fish." Fish living long-term in clear water are similar to humans living in a desert without vegetation or wetlands; the living environment is extremely harsh. The harms of clear-water fish farming caused by large water exchange are many, such as:
A. The feces excreted by fish in the farming water body cannot be decomposed in time due to the lack of plankton and decomposing microorganisms, and thus accumulate in large amounts;
B. Dissolved oxygen in the water body is continuously consumed by the respiration of farmed organisms, while at the same time lacking supplementation from photosynthesis, which easily leads to a rapid decrease in dissolved oxygen in the water;
C. Harmful pathogens such as Saprolegnia and common eel parasites (such as Ichthyophthirius, Dactylogyrus, Trichodina, etc.) are most likely to reproduce in large numbers in this monotonous clear-water system before algae and other photosynthetic plankton and zooplankton, easily causing explosive fish diseases;
D. Frequent water exchange during farming not only wastes water resources, but each new batch of water is a new environment for the fish, causing the fish to be frequently in a state of conditional stress, seriously affecting their feeding and growth;
E. Large amounts of water exchange make it difficult to keep the farming water temperature constant, not only causing stress to fish but also increasing heating energy consumption and raising production costs;
F. Frequent water exchange often brings pathogenic bacteria, viruses, and parasites through the water source, greatly increasing the probability of fish disease;
G. Fish have no sense of security in clear water and are easily stressed by the environment, and their feeding efficiency is also greatly reduced as a result.
Counting these drawbacks of large water exchange, it is not difficult to understand why the controllable ecological farming model does not adopt large water exchange. Controllable ecological farming emphasizes what people often say: "To raise fish, first raise the water." The so-called "raising water" means reducing water exchange as much as possible or even not exchanging water during the farming process, and intentionally cultivating large amounts of phytoplankton, zooplankton, and decomposing microorganisms in the farming water body, so that the water body forms an ecosystem with biodiversity, allowing various microorganisms to efficiently digest fish feces and other harmful substances in the water, purify water quality, and create a balanced and stable good ecological environment for fish, effectively avoiding the various drawbacks caused by clear-water fish farming.
5. Why can't water disinfectants and other medications be used in controllable ecological farming?
Answer: One of the most important aspects of controllable ecological farming technology is cultivating large amounts of zooplankton, phytoplankton, and decomposing microorganisms in the farming water body. Sometimes "probiotics" are also added to the farming water body. The purpose is to achieve water quality self-purification through the water body's ecosystem, while inhibiting outbreaks of harmful pathogens and parasites, and protecting fish safety. If water disinfectants, antibiotics, or insecticides are used during farming, various microorganisms will die in large numbers, and the carefully established water body ecosystem will be damaged or even collapse. When the aquatic ecosystem is out of balance, harmful pathogens and parasites in the water always take the lead and reproduce in large numbers, subsequently causing pests and diseases. Abuse of medication will fall into a vicious cycle of "medication - water exchange - disease - medication." Fish often develop various drug-induced diseases, and there may be a risk of excessive drug residues in fish. Controllable ecological farming requires a stable, diverse biological system, and the use of any medication may damage this system or even cause serious consequences.
6. Why does feed formula affect controllable ecological farming?
Answer: In a controllable ecological farming system, the digestive capacity of microorganisms and the amount of fish feces discharged are in a dynamic balance. Excessive feces discharge will cause micro-ecological imbalance and produce adverse effects. Whether the feed formula is reasonable directly affects the feed digestion and absorption rate and the nutrient content in fish feces. Long-term intake of feed with an unreasonable nutritional formula by eels will cause poor health, which in turn affects feed digestion and absorption rate, increases the burden on the ecosystem, and reduces the fish body's resistance to disease. In addition, if antibiotics are added to eel feed, they will kill beneficial bacteria in the eel intestinal tract and also affect the eel's digestion and absorption capacity. Choosing a good feed formula helps improve its digestion and absorption rate. Adding fermented soybean meal or other active fermentation products to the feed formula is very beneficial for cultivating beneficial bacteria in the eel intestinal tract and helping eels digest and absorb.
7. Why does controllable ecological farming require reasonable density?
Answer: In a controllable ecological farming system, fish feces mainly rely on microorganisms in the water for timely digestion, and the water body ecosystem's capacity to digest fish feces has a limit. If the farming density is too high, the feces produced may exceed the digestive capacity of the ecosystem, the ecological balance will be broken, and water quality will deteriorate. To avoid this situation, controlling appropriate farming density is crucial. Preliminary experiments show that under conditions of no water exchange, no sewage discharge, and relatively constant temperature, a juvenile eel rearing density of 500-800 fish/m2 is feasible; for adult eel farming under conditions of no water exchange and no sewage discharge, the stocking density can reach 6-8 kg/m2.
8. How can the controllable ecological farming model achieve higher-density farming?
Answer: In the controllable ecological farming model, the key to achieving higher-density farming is how to break through the digestive limit of the water body ecosystem for feces. This is also the issue readers care about most. We know that the digestive limit of microorganisms cannot be broken through. The only solution is to use physical methods to separate part of the fish feces from the water body, reduce the burden on microorganisms, and achieve balance under human control. This is a key link in controllable ecological farming. There are many specific separation methods, commonly used ones such as micro-particle filtration, constructed wetland filtration, and cyclone foaming separation. The higher the efficiency of manually separating fish feces, the higher the stocking density that can be achieved.
--------------------------------------
:guzhang::guzhang:
--------------------------------------
Eel rice is delicious