What are the common problems during rice field eel (Monopterus albus) farming?

1. Blindly pursuing excessive scale
Stimulated by the high profits of rice field eel farming, many farmers spare no effort to expand their farming scale in order to obtain higher returns in a short period, such as how many cement ponds they build and how many cages they make. Because the farming scale is large, in order to obtain the corresponding number of seedlings and feed, they are not strict in checking the introduction of rice field eel seedlings and the sources of animal feed for rice field eels. The result is usually that the purchased seedlings are of uneven quality and inconsistent sizes; because animal feed is also in severe shortage, strict checks cannot be carried out, and the final result is a low survival rate of eel seedlings after stocking. The surviving eel seedlings, because feed supply cannot be guaranteed and feed quality is poor, frequently suffer from eel diseases. Blindly expanding the farming scale and seeking both size and completeness without fully considering every link in the rice field eel farming process means that after a busy year, let alone making money, suffering fewer losses is the best result.

2. Not being strict in checking purchased seedlings
At present, no substantial breakthrough has been made in large-scale breeding technology for rice field eel seedlings, and the rice field eel seedlings purchased by farmers are basically wild-caught. Among the commercial eels sold on the market, there are artificially farmed ones and those caught by cages, electrofishing, and drugs. Those that can be used as eel seedlings for farming mostly come from these capture methods: cage capture, electrofishing, and drug capture. How to distinguish and select eel seedlings is the key to the survival rate of rice field eel farming and also the key to successful farming. The capture method is the key factor determining whether eel seedlings are suitable for farming. Rice field eel seedlings caught by hook fishing are easy to identify and remove because their mouths are injured, but eels caught by drugs or electrofishing are not easy to distinguish with the naked eye in a short time and mostly begin to die in large numbers within 7—10 days after being put into ponds. If rice field eels caught by nets or cages stay in the nets or cages for too long, the mortality rate after entering ponds is also quite high. If rice field eels caught by nets or cages, during the temporary holding period of the catcher, suffer from fever, acidosis, and other problems due to dense holding, deteriorating water quality, and other reasons, they often show symptoms similar to other diseases after entering ponds, and treatment is often ineffective. In addition, the period when large numbers of eel seedlings are captured is exactly the high-temperature season. If temporary holding and transportation are improper, it will also cause large numbers of rice field eels to die after being put into ponds.

3. Incomplete feeding training
In the wild, rice field eels feed by hiding by day and coming out at night, are inclined to carnivory, and like to eat natural live bait. When farming rice field eels artificially, if the eels cannot be made to change their feeding habits, this will have a major negative impact on farming results and the utilization rate of artificial feed.
Through feeding training, the first goal is to solve the problem of rice field eels preferring live bait. Rice field eels are carnivorous animals. If only a single animal feed is given, the eels will become averse to other feeds. If feeding training is done well in the early stage of rearing so that the eels eat artificial compound feed, then in future farming they can be fed a complete-price artificial compound feed with wide sources, low price, and high flesh gain rate, which is also beneficial for future disease prevention and treatment and for administering medicated bait. The second goal is to adjust the feeding time of rice field eels. Wild rice field eels mostly come out of their holes to seek food at night. Through feeding training, gradually adjust the feeding time so that the eels feed during the day.
Feeding training for rice field eels usually takes about 40 days. Some farmers, at the intermediate stage of feeding training, see that some rice field eels feed on artificial compound feed during the day and then stop training. But this only means that some rice field eels have developed a conditioned reflex to the training; many eels are still in the transition period of feed acceptance, and the feeding training has not been fully completed.
Doing feeding training well is very important for disease prevention and treatment and for administering medicated bait in later rice field eel farming. The best result of feeding training is: rice field eels feed during the day, can compete for artificial pellet feed, and develop a feeding conditioned reflex toward the feeder.

4. Unscientific feed feeding
Most farmers mainly feed live bait such as earthworms and small trash fish, and few feed complete-price artificial compound feed. Rice field eels fed live bait such as small trash fish mostly grow slowly because of incomplete nutrition, and the feed conversion ratio is high. In addition, because the production of live bait lacks continuity, cannibalism among rice field eels is relatively serious, and enteritis and bacterial tail-rot disease occur from time to time. Even among farmers who feed compound feed, feeding is highly arbitrary, not following the "four fixed" and "four look" feeding principles, and the daily feeding amount is not flexibly controlled according to season, water temperature, and weather changes. The final result of arbitrary feeding is: the utilization rate of feed by rice field eels decreases, increasing the feed conversion ratio; the eels are sometimes full and sometimes hungry, inducing bacterial enteritis; the eels chase and bite each other, and bacterial tail-rot disease occurs throughout the year; the harvested rice field eels are uneven in size and inconsistent, and yield is low.

5. Not paying attention to water quality regulation
In artificial rice field eel farming, failure to pay attention to water quality regulation often results in frequent eel diseases, reduced feed utilization by the eels, slow growth of the eels, and low farming efficiency.
To regulate water quality, first, regularly add fresh water to keep the pond water fertile, lively, tender, and refreshing, with sufficient dissolved oxygen. Second, regularly splash quicklime over the whole pond to regulate water quality while killing pathogenic bacteria in the pond. Third, regularly splash microbial preparations such as photosynthetic bacteria over the whole pond to improve the microbial structure in the pond and improve water quality.
Regulation of farming water level. Many farmers, when adding fresh water, easily neglect the regulation and control of pond water level and water temperature. If the pond water level is too shallow, it easily causes a large temperature difference between day and night in the pond water; if the pond water level is too deep, rice field eels must often leave their burrows and come to the water surface to breathe air, affecting their growth; if the temperature difference between the added fresh water and the water in the farming pond is too large, it will cause cold disease in rice field eels.

6. Delayed disease control
The prevention and control of rice field eel diseases and pests should focus on prevention. Once disease occurs, treatment is relatively difficult. The focus of prevention is to strengthen daily management, adhere to the "four fixed" and "four look" feeding principles, and reduce opportunities for rice field eels to be injured and infected. The main measures to prevent rice field eel diseases include: disinfecting the fish body before eel seedlings enter the pond, controlling the stocking density of rice field eels, maintaining appropriate pond water depth, regularly adding fresh water, regularly splashing quicklime over the whole pond, and regularly feeding medicated bait.
In the early stage of disease onset in rice field eels, shallow-water treatment should be carried out, and while the eels can still feed in the early stage of disease, medicated bait should be fed in time for treatment. In the early stage of disease onset, attention should also be paid not to carry out large drainage and large-scale irrigation of pond water, so as to avoid stress reactions in the eels caused by large changes in water level, which can worsen the condition and affect the therapeutic effect of drugs.
The rice field eel is a relatively special species among fish. It can survive out of water for a relatively long time and will not die if not fed for a long time, giving people the impression that it has strong vitality. Many farmers therefore neglect the prevention of diseases and pests in rice field eels. In fact, rice field eels are very fragile and easily harmed. Environmental changes, nutritional deficiency, injury, and invasion by pathogens can all cause disease in rice field eels, affect their growth and survival rate after rearing, and ultimately affect farming efficiency.