Breeding and stocking of eel fry

The cultivation of eel seedlings is the production process of turning eel seedlings into more than 10 grams of eels. This stage needs to go through the cultivation of three different types of ponds, such as primary pond, secondary pond and tertiary pond. Eel species are the basis of adult eel culture, and the quantity and quality of eel species directly affect the quality of adult eel culture. Therefore, in order to develop eel production, we must first do a good job in the cultivation of eel seedlings. In order to ensure the smooth progress of eel seedling cultivation, in addition to all the preparatory work mentioned above, it is also necessary to do a good job of the following production links.

Eel fry restocking time

Since eel seedlings can only begin to feed and grow when the water temperature is above 15 ℃, it is more suitable for eel seedlings to be reared in open ponds when the natural water temperature is above 13 ℃. In this way, eel seedlings can be eaten and domesticated when the water temperature rises after short-term temporary cultivation. The stocking time of eel seedlings in Fujian and Guangdong is about the beginning of March. In eel farms with heating conditions or warm water supply, the release time of eel seedlings should be as early as possible, which can prolong the breeding period and improve the yield and quality of eel species.

Stocking density of eel seedlings

Due to different culture methods, the stocking density of eel seedlings is also different. In general, the stocking density of water-stop ponds is 150g ~ 300g / m2, and that of running ponds is 500g ~ 1000 g / m2. The growth of low density stocking is faster and the survival rate is high. Adaptation of eel seedlings to the environment

Eel seedlings are in a state of fatigue after long-distance transportation, and the temperature difference between the seedling container and the pool water is too large (especially the heating breeding pool), so it is necessary to have an adaptive process. The specific method is to put the eel seedling box on the edge of the pool, gradually drench the eel seedling box with pool water, and put it into the cage in advance when the eel seedling body temperature is close to the pool water temperature (generally no difference of 5 ℃). If you use a nylon bag for oxygen transport, you can first put the nylon bag with seedlings into the pool, and then remove the bag and put the eel seedlings into the cage when the bag temperature is close to the pool water temperature. Eel seedlings are generally temporarily raised for 0.5 hours to 1 hour (turn on the aerator). After normal activity, the dead seedlings and dirt are removed, weighed and counted and put into each eel seedling culture pond.

Counting and weighing of eel seedlings

In order to control the stocking density of eel seedlings, it is necessary to count and calculate the weight, specification and Mantissa of each first-class pond. The specific method is: first, gently stir the eel seedlings in the cage, then randomly sample 2 ~ 4 times, weigh 50 grams each time, count them with a small bowl or spoon, and then work out the average specification. Finally, the tail number of eel seedlings per kilogram is calculated, and the average specification is obtained.

Disinfection of eel seedlings

The young eel has a delicate physique and is easy to be bruised and infected with mold and bacterial diseases in collection, temporary cultivation and transportation. Therefore, disinfection must be carried out during stocking. The method of disinfection is medicine bath, one is to use container for medicine bath, the other is to sprinkle medicine bath in the whole pool.

1. Disinfection time: the medicine bath in the container was carried out in front of the eel seedling pool, and the whole pool was sprinkled and disinfected in the evening after the eel seedling went down the pond.

2. Disinfection drugs and concentration: the commonly used drugs are salt, methylene blue and so on.

3. Disinfection steps and methods: when using container medicine bath, it is generally carried out in a large water tank, so it is also called cylinder bath. The specific method is to first put 300 kg ~ 400 kg of clear water in the tank, then dissolve it in a small amount of water and then pour it into the tank according to the proportion of drug dosage, and turn on the aerator for aeration, constantly stirring the water, so that the liquid is evenly distributed, and then weigh about 5 kg of eel seedlings together and immerse them in the traditional Chinese medicine bath for 10 ~ 15 minutes, then the eel seedlings can be taken out and released. Sprinkle the medicine bath in the whole pool in the evening, sprinkle the medicine directly in the first-class pool after dissolving, turn on the aerator to stir the water, so that the liquid is evenly distributed.