How to Raise Rice Field Eels? A Detailed Explanation of Key Breeding Techniques

The rice field eel (Monopterus albus) is a rapidly developing premium species in China's freshwater aquaculture. In the southern regions of China, rice field eels have always been regarded as a top-grade dish, and among the Chinese people they enjoy the reputation that "rice field eels at Minor Heat are as good as ginseng". So how do you raise rice field eels?

1. Pond Preparation

The core technique of still-water, soil-free ecological rice field eel farming is to use the principles of biodiversity and symbiotic mutual benefit, thereby achieving the goals of increasing the survival rate and growth speed of rice field eels and preventing and controlling pests and diseases. To achieve still-water, soil-free rice field eel farming, you must first create a quiet, comfortable home for the rice field eels. The pond area is generally about 18 sq m, with a pond height of 40-50 cm, which makes management easier. The water inlet is set in the south wall, and the drainage outlet is at the bottom of the pond near the north wall, so that waste can be discharged thoroughly. To prevent the pond water from rising sharply during rain, an overflow outlet should also be set in the north wall at a height of about 30 cm from the pond bottom. Rice field eels are very good climbers, so when building the pond, be sure to build a wall edge of about 10 cm to prevent accidents in which the rice field eels stage a great escape to freedom. Growing aquatic plants in the rice field eel pond can not only regulate and purify the water quality, but also provide the rice field eels with a place to rest and shelter from shade and rain. More importantly, it can help prevent and control pests and diseases. Our experiments confirmed that the flavonoids contained in alligator weed, in particular, can have an effect on rice field eel pests and diseases similar to that of gentamicin. When putting in aquatic plants, the area covered by the plants should not be too large; at least one quarter of the space should be left around the edges so that the rice field eels can fully enjoy their freedom.

2. Water Quality Management 

The quality of the water is very important, so how do you judge whether the water quality is good or bad? One way is by the color of the water. Generally speaking, yellow-green is better. If it is black, brown, or grayish-white, artificial farming results are generally poor. We can also judge with the naked eye. Generally, being able to see the bottom is better, but it must not be clear; when the water is clear, there are no fish. River snails are very sensitive to oxygen. If there is a lack of oxygen, they will cluster together, and at that point the water should be changed promptly. Usually, keeping the water level at about 30 cm is sufficient. In addition, whether in the north or the south, overwintering protection work must be done well. Although it is very cold and ice has formed on the surface, as long as there is sufficient oxygen, the rice field eels can overwinter safely.

Compared with the still-water, soil-based rearing method, this has the advantages of simple operation, faster growth, lower cost, higher yield, and easier harvesting, but the required condition is that there must be a continuous flow of water; otherwise, the water quality is very likely to deteriorate and cause disease and death.

3. Artificial Feeding

Yellow mealworms are the favorite food of rice field eels, so using yellow mealworms as a lure to train rice field eels to eat compound feed is a good method. Generally, on the first day, yellow mealworms account for 80% and other compound feed accounts for 20%. After that, the amount of yellow mealworms is reduced by 10% per day, and the compound feed is increased by 10% per day, balancing meat and plant ingredients. During artificial feeding, because a large amount of feed is given, the feces excreted by the rice field eels easily pollute the water quality, so new water should be added frequently to keep the water fresh. In spring, change the water once every 7 to 10 days; in summer, change the water once every 3 to 5 days.

Rice Field Eel Farming Costs

1. Pond construction cost: 200 yuan;

2. Farming 20 kg of wild rice field eels, with medium-sized summer rice field eels (30-50 g per fish) at 15 yuan per kg, costs 300 yuan;

3. After 5-8 months of rearing, the body weight of rice field eels can increase by 3-5 times. Calculating by a 3-fold weight gain, 20 kg of rice field eels can gain 60 kg. At a feed cost of 8 yuan per 1 kg of rice field eel weight gain (if large amounts of earthworms and the like are used, the cost can be greatly reduced), the feed cost required is 480 yuan;

4. Medicines and other expenses: 100 yuan. The total of the above four costs is 1080 yuan.

Precautions for Rice Field Eel Farming

1. Buying seedlings indiscriminately.

At present, the number of artificially bred rice field eel seedlings in China is limited. Some farmers go to Sichuan and other places to buy so-called artificially bred high-priced rice field eel seedlings, at as much as 120-160 yuan per kg. Some sell four rice field eel breeders for more than 400 yuan, more expensive than gold. Can you make money buying breeders like this? Moreover, because these seedlings are stored for long periods at high density in unscientific ways by vendors and are repeatedly transported, most have already contracted fever disease, and the mortality rate during farming can reach 90%-100%. Therefore, when buying seedlings, be sure to identify them carefully. Generally, for artificial rice field eel farming, you can choose to introduce excellent breeding rice field eels for semi-artificial reproduction or natural reproduction to obtain eel fry, or you can select high-quality eel fry locally for fattening and farming.

2. Treating reference books from bookstores as magic treasures.

At present, although there are already about 10 versions of rice field eel farming technical books in China, their contents basically copy general fish farming techniques or trot out empty theories to mystify things. There is very little truly practical experience, and it is very difficult to succeed by relying only on these techniques. Beginners in rice field eel farming had best visit well-known rice field eel farming enterprises or large rice field eel farming households on site to learn and master truly feasible rice field eel farming techniques.

3. Mixed culture of large and small eels.

When large and small rice field eels are mixed in the same pond (cage), the small eels do not dare to compete for food, and their constitution gradually weakens and they may even die. When bait is insufficient, rice field eels will eat each other. Therefore, when large and small rice field eels are mixed, although the large eels grow quickly, the overall yield is too low.

4. Pond water too deep.

Rice field eels differ from ordinary fish in that their main respiratory pathway is not through the gills but through the pharyngeal cavity. Also, because rice field eels have no swim bladder in their internal structure, they cannot float and stay at will in different water layers and must expose themselves above the water surface to breathe air. If the pond water is too deep, rice field eels need to swim frequently to the surface to breathe, consuming a great deal of energy and affecting normal life and growth. For pond-raised rice field eels, the water depth should be about 20-30 cm according to body size, while for cage-raised eels, aquatic plants should fill the entire cage as much as possible to provide good habitat and breathing conditions for the rice field eels.

5. Applying manure excessively.

The water body of the eel pond is small, and applying manure very easily spoils the water quality and induces disease.

6. Neglecting to cultivate aquatic plants.

Aquatic plants can prevent heat and lower temperature for rice field eel farming, purify water quality, and provide excellent concealed places for rice field eels. An eel pond without aquatic plants cannot create a good ecological environment, and rice field eel farming is also unlikely to succeed, making it very difficult to achieve high yield and high efficiency.

7. Too much “vegetarian” and lacking “meat”.

Some farmers use plant-based baits such as wheat bran, rapeseed cake, bean dregs, rice, and green vegetables to feed rice field eels. When severely hungry and lacking bait, rice field eels will also eat a small amount, but the nutrition cannot meet the needs of the rice field eels' life activities, let alone growth and weight gain, and the rice field eels will gradually become thin and weak and become diseased and die. Rice field eels are carnivorous fish, so animal feed or complete compound feed should be given.

8. Changing feed frequently.

Farmers often change the type of bait frequently because there is no guaranteed supply of bait and they gather whatever they can find. Rice field eels have a certain fixed preference for bait. If the type of bait is suddenly changed, the rice field eels find it hard to adapt and refuse to eat

What Are the Common Diseases of Rice Field Eels

1. Enteritis disease

1. Symptoms: redness and swelling, bleeding in the gill area, the head turning black and extending above the water surface to breathe, congestion in the oral cavity, and red spots appearing on the abdomen. It is prevalent from April to July, highly contagious, and develops quickly. The course of the disease is short and the mortality rate is high.

2. Prevention and treatment: ① During the disease season, splash 1 g/m3 of bleaching powder in the water body every 10-15 days. ② For every 50 kg of eels, mix 5 g of garlic into the bait and feed for 6 consecutive days; or mix 2 g of oxytetracycline into the bait and feed.

2. Hemorrhagic disease

1. Symptoms: the body surface shows dotted, patchy, or diffuse congestion, more obvious on the abdomen. Redness and swelling, and in some cases there is blood-like mucus in the oral cavity; when the tail is lifted, blood-stained water flows from the mouth.

2. Prevention and treatment: ① Dissolve 0.2 mg/l-0.25 mg/l of oxytetracycline in water and splash over the whole pond. ② For every 5 kg of eels, mix 1 g-2 g of oxytetracycline with mussel meat and feed.

3. Tail rot disease

1. Symptoms: the tail becomes congested and inflamed, then the muscle necrotizes and ulcerates; in severe cases, the tail rots away and the tail vertebra is exposed.

2. Prevention and treatment: ① Splash oxytetracycline at 0.2 mg/l-0.25 mg/l over the whole pond. ② Soak and disinfect diseased eels with 0.25 unit/ml chlortetracycline.

4. Neoechinorhynchus disease

1. Symptoms: the worm's proboscis firmly penetrates into the intestinal mucosa of the diseased eel to absorb nutrients, causing intestinal congestion and inflammation in the rice field eel, blocking the intestinal tract, and causing some tissue hyperplasia or hardening.

2. Prevention and treatment: ① Splash 90% crystalline trichlorfon at 0.1 mg/l over the whole pond. ② For every 1 kg of rice field eels, mix 0.04 g-0.1 g of 90% crystalline trichlorfon with 1 kg of earthworms and feed.