Domestication techniques of wild ricefield eel seedlings

At present, there are two kinds of cultivated Monopterus Albus in China, one is tropical Monopterus Albus from Thailand and Vietnam, this kind of Monopterus Albus has strong fecundity, miscellaneous diet and fast growth, so it is an excellent species from the point of view of culture. However, the poor market sales performance is due to its rough meat and poor taste, so the market price is very low, which is less than half of the price of local ricefield eel of the same specification in the same period, and the sales channel is narrow and the bulk sales are not smooth. At the same time, the most fatal factor in the introduction of tropical ricefield eel into domestic breeding is that it can not survive the winter naturally. The other is Chinese native temperate ricefield eel, which is mainly distributed in the north of the Pearl River Basin and the south of the Yellow River Basin, in which the Yangtze River Basin is the most distributed, and the natural habitat is mainly in shallow water zones such as fields, ditches and ponds.

For the farmed seedlings, on the one hand, the small size wild eel seedlings can be collected directly from the natural environment, on the other hand, the breeding eel seedlings can be purchased from the rice field eel breeding farm. From the perspective of culture effect, the survival rate and weight gain ratio of artificially propagated seedlings are high, and they can directly eat the special full-price feed for Monopterus Albus, but the disadvantage is that the price is high. The advantage of wild eel seedlings is that the price is cheap, but the survival rate and weight gain are greatly affected by random factors, and wild eel seedlings have been gradually scarce in some areas. Therefore, farmers can choose according to their own situation. At present, most of the rice field eel farmers in most areas choose wild eel seedlings as the source of breeding seedlings, but the fishing operation of wild rice field eel is required to enter the market directly, and the impact of the whole process on eel seedlings is more serious. however, the general farmers do not have enough understanding of this problem. Therefore, it is extremely necessary to standardize the procedures for the use of wild seedlings, but on the other hand, even if it is a standardized operating procedure, some of these links are uncontrollable in many cases. Therefore, the use of wild eel seedlings must be cautious.

Origin and selection of eel species

The source and selection of eel species are directly related to the input and its risk, which is the first problem to be solved in the cultivation of ricefield eel. At present, there are several main sources of eel species in production.

1. Capture directly from the wild

Eel cages can be used to catch rice fields and shallow water ditches from April to October every year, especially in muggy days or after thunderstorms, the most rice field eels come out at night than during the day. One person can take 200 eel cages at a time. Put it into the ditch field at night or after a thunderstorm, and the rice field eel can be caught in a few hours. When catching ricefield eels with eel cages, we should pay attention to two points: first, it is better to use earthworms as bait, taking eels from each cage 2 or 3 times a night; second, when the eel cage is put into the water, the tail must be slightly exposed to the water, so that the eel can breathe air in the cage, otherwise it will suffocate or suffer from anoxia. The eel cage will be taken back at dawn, the big ones will be sold, and the small ones will be used as species. The species of eel caught by this method have no damage to their health and have a high survival rate. Another method is to light the lamp at night, patrol along the edge of the ditch on the ridge of the field, find eels looking for food, catch them with eel traps or catch them with their bare hands. When catching, try not to damage the eel species as much as possible. Eels caught should be released immediately.

2. Market procurement

When purchasing eel species in the market, you should choose a strong and harmless rice field eel. The species of caged eel which has been in the temporary state of changing water should be selected as the breeding object. Monopterus Albus poisoned by pesticides and caught by drugs can not be raised (most of the eels caught by drugs have small red spots on the abdomen, and the red spots become more obvious over time, and their vitality is poor). Generally speaking, rice field eel varieties can be divided into three types: the first kind of eel is yellow with large spots, and this kind of eel grows fast; the second kind of body color is green and yellow, and this kind of eel grows generally; the third kind of body color is gray and the spots are fine, so it does not grow fast. Three species of eel should be raised separately. The weight gain of adult eel produced by eel species per kilogram is as follows: the first is 1 ∶ (5 × 6), the second is 1 ∶ (3 × 4), and the third is 1 ∶ (1 × 2). The best size of eel species is 20 to 50 eels per kilogram, the specification is too small, the survival rate is low, and it can not be listed in the same year; the specification is too large, the meat gain multiple is low, the unit net yield is not high, and the economic benefit is low. However, this is not absolute, what specifications of eel species have to take into account market factors. If the price of large-size commodity eel on the market before and after the Spring Festival is very high, breeders can also properly consider raising large-size eel species, or even adult eel.

3. Seedling cultivation of semi-artificial propagation

The main results are as follows: (1) simulate the natural spawning environment in the field and let it reproduce naturally in the culture pond. At the end of each year, from the artificially cultivated adult eel, individuals with strong physique, tail weight of 100g to 200g and yellow and glossy body color are selected to spend the winter in a pool rich in organic matter, and then spawn naturally from June to July of the following year. When the water temperature in the pond is above 15 ℃, the feeding of this batch of eels should be strengthened. During the breeding period, we should pay close attention to the eggs laid and the hatched eel seedlings. It is found that the eggs can be taken out for special hatching, and the seedlings should be fished out in time and reared according to different specifications in order to prevent eating small and eating each other. In the breeding pond, zooplankton can be cultivated with organic fertilizer such as chicken manure, and then eel seedlings can be put into the pond to let eel seedlings grow on zooplankton. If there is a shortage of zooplankton, you can help feed some boiled egg yolk. As soon as the young eel begins to eat, it gradually disperses its activities.

(2) the fertilized eggs of Monopterus Albus were collected in the wild and then hatched into seedlings artificially. Every year at the height of summer, some lakeside swamps, rural ditches and rice fields can often be seen floating on the surface of the water, which may be the hatching nest of Monopterus Albus. When this phenomenon is found, it should be picked up gently with a ladle or rice spoon and placed in a basin or bucket filled with new water. After that, the eel eggs are carefully placed in the eel egg incubator to hatch. The management during incubation is the same as that during artificial breeding.

(3) collect wild eel seedlings directly in the field. Water hyacinth is raised in ditches frequented by ricefield eel, and wild eel seedlings can be collected from late June to early July. The method is to spread a plastic mesh cloth on the ground first, and use the sea to fish the water hyacinth onto the net cloth. The eel seedlings originally hidden in the water hyacinth root will automatically drill out and fall on the net cloth. The collected wild eel seedlings can be cultured in the eel seedling pond. Another method can also receive wild eel seedlings. In the middle of June, horse dung, cow manure and pig manure can be mixed with soil in advance in the living waters of Monopterus Albus to make a massive distribution of fat water area in the water. Many silk earthworms can grow in the fat water area, and after eating, the young eel will automatically drill into these fat water areas to find food. at this time, the cheat sheet net can be used to catch and put into the young eel breeding pond.

4. seedling cultivation of full artificial propagation.

The eel seedlings that will be artificially propagated will be artificially cultivated by feeding water worms and so on.

Seedling collection technique of wild ricefield eel

1. Means of transportation before collection of eel seedlings

Iron boxes with a capacity of 100 kg or frames lined with plastic film, PVC mesh sheets with more than two fingers, well water or clean river water (well water should be put into containers 10 hours in advance), weighing tools, tight-eye mesh bags, braided baskets.

2. Collection method of eel seedlings.

The main results are as follows: (1) the best fishing method is cage fishing, and electric fishing can be selected appropriately.

(2) subscriber purchase requires that the ricefield eel caught by the catcher should be stored in the proportion of 1 part of ricefield eel with 4 parts of water every day, and the time from cage to storage should be controlled within 1 hour as far as possible.

(3) the farmers must buy back the rice field eel caught that day every morning, and the journey time shall not exceed 4 hours. At the time of acquisition, the container holds water to 2/3, with 0 and 5 kilograms of polyethylene mesh built in. When the eel seedlings were transported back, the water was changed immediately and thoroughly, and the proportion of water changed was more than 1 ∶ 4. In the process of washing, remove the injured and frail eel seedlings. An hour later, the rice field eel was sorted into two categories: less than 25 grams and 25 grams and 50 grams, and then put into the eel pond. During the whole operation, the change of water should avoid excessive temperature difference (less than ±2 ℃).

Domestication techniques of wild ricefield eel seedlings

1. The significance of domestication

According to the natural diet of Monopterus Albus, domestic farmers generally feed fresh bait for artificial culture, including earthworms, small mixed fish, clams, snails or trapping insects. Its advantage is that Monopterus Albus can quickly form feeding habits, but the disadvantages are also obvious, such as low multiple of weight gain, quantity can not be stable supply for a long time, especially in large-scale culture, this limitation is more difficult to overcome.

Whether to use artificial compound feed to feed Monopterus Albus is a problem that must be solved in large-scale breeding of Monopterus Albus. There are also some farmers who prepare some artificial bait for feeding, but the feeding rate and weight gain are not ideal because of the lack of understanding of the changing process of eating habits, the comprehensive nutrition of artificial diet and the preparation method of artificial diet. After years of experiments by researchers and on the basis of repeated studies on the digestive function of Monopterus Albus, the problems of nutritional comprehensiveness and eatability of artificial diet of Monopterus Albus were successfully solved. The large-scale production test shows that using special bait, Monopterus Albus has high feeding rate, fast weight gain and low feed coefficient.

2. Preparation before domestication

Purchase fresh mussels and put them in ponds for temporary storage. Special artificial feed for ricefield eel. Freezer: the mussel meat should be frozen before use. Meat grinder (large) with two mold holes (3mm, 6mm)

3. Design and construction of domestication pond

The domestication pond is mainly used for the domestication of ricefield eel, which is made of cement and brick. The domestication area is generally small, 2 square meters per pool, with a height of 40 centimeters and 60 centimeters. Two water intake holes are arranged on one side of the pool, and two drainage holes are arranged on the other side of the pool. One drainage hole is as high as the bottom of the pool, and the other is 15 centimeters higher than the bottom of the pool.

4. Domestication methods

The purpose of this technique is to establish the hunger of ricefield eel and make a suitable feed shape to improve the success rate of domestication of ricefield eel. Fresh clam meat was selected as domesticated bait, which was frozen and processed into minced meat with a 6mm mold hole grinder. Clam meat can not be effectively digested by ricefield eel, but it is one of the favorite bait for ricefield eel. Feed at 5pm to 7pm every day, once a day, and the feeding amount should be controlled within 1% of the total weight of eel seedlings. This number is far less than 5% to 6% of the rice field eel's full food intake, so the rice field eel is always in a state of hunger, creating a good opportunity for the establishment of a population concentrated feeding condition reflex. When feeding, first mix the minced clam with clear water, then sprinkle evenly. Three days later, it was observed that Monopterus Albus was fed vigorously, that is, it was fed at a fixed point, usually 4-6 points in each pond, and continued feeding for two days, and the feeding amount was still 1%. At this time, Monopterus Albus could be eaten in 3 minutes. It was changed to artificial bait on the sixth day.

The rapid conversion of this artificial compound feed is by no means effective for any artificial bait, and this special artificial compound feed must have a special feed processing shape and composition. First of all, the carefully prepared rice field eel feed 50 kg was added with 8% fresh clam meat pulp (processed by 3mm 4mm meat grinder) and an appropriate amount of Wanlong 5, mixed with the above proportion, stirred fully by hand or with a mixer, then pressed into a soft strip feed with a diameter of about 3mm and a length of 3cm with a 3mm mold hole grinder, which was slightly air-dried and ready for feeding. When feeding, it is directly sprinkled into the fixed-point feeding area, the feeding amount is about 2%, and it is fed at 5: 7 pm every day. Special attention should be paid to feeding in 15 minutes, so as to improve feed efficiency and reduce the load of carriers. The feeding effect of this combination of artificial bait is very ideal, and the growth rate of Monopterus Albus is fast.