Breeding of Yellow Catfish Fry

It takes about half a month to cultivate the fry of Pelteobagrus fulvidraco (commonly known as spray) from 1.5 cm to 1.2 cm in length to 5 cm and 6 cm in size. The cultivation methods at this stage include pond cultivation, running pool cultivation and cage cultivation. Compared with the fish fingerling cultivation, the fish fry stage requires higher technical content. Therefore, great attention must be paid to the cultivation of fish fry.

(1) conditions and requirements for nurturing ponds or cages

1. The structure of the running water culture pond the density of the fish fry cultivation in the running water tank is higher, so the requirement of the culture pond is higher. The running water cultivation pond should be a small cement pool with an area of about 10 to 30 square meters, with a maximum of no more than 50 square meters and a depth of 1 meter. The best shape is rectangle and circle. The bottom of the pool is required to be basically flat, with a slope of 3 °~ 5 °, convenient for entry and drainage, and equipped with water intake screen window and anti-escape screen window.

two。 The conditions of pond culture require that fish fry ponds should be conducive to fry activity, growth, feeding management and net-pulling operation. Generally speaking, the following conditions should be met: adequate water source, fresh water quality, convenient injection and drainage. The shape of the pool is neat, with an area of 0.5-1.0 mu and a water depth of 50-100 cm, shallow in the early stage and deep in the later stage. The bottom of the pool is flat, there is an appropriate amount of silt (about 10 cm), and there are no weeds on the bottom and edge of the pool. Set up a rectangular fish collecting culvert at the outlet (either cement pond or soil pond) to facilitate centralized fishing of fish fry. The dike of the pool is strong and does not leak. The surrounding environment is good, the fish fry pond is sunny and the light is sufficient. Pond water quality turbidity can not be large, pH7~8, dissolved oxygen content is more than 5 mg / L, transparency is 30-40 cm.

3. The cage structure of fish fry requires that the net mesh of fish fry should be different according to the size and size of fish fry. The mesh of hatched larva cage is 40cm 50 mesh, 0.9cm 1.0cm cage 20mesh 30 mesh, 3cm fry cage 10mesh 20 mesh. The shape of the cage is either rectangular or square. The size of the cage is determined according to the size of fish fry in different periods. When the fry is about 1 cm, the cage is 3 square meters, when the fry is more than 2 cm, the cage is 5 square meters, and when the fry is about 5 cm, the cage is 10 square meters. When setting the cage, the upper and lower four corners of the cage should be firmly fixed on the support frame of the cage.

(2) preparation before releasing fish fry

The main purpose is to clean and disinfect the ponds where fish fry are cultivated, as well as to cultivate fertilizer and water.

1. Pond cleaning disinfection is an important measure to improve the environmental conditions of the pond and improve the survival rate of fish fry. After raising fish in the pond, a large amount of undecomposed organic fertilizer residue and fish leftover bait and feces are deposited at the bottom, the bottom silt increases, and a large number of harmful microorganisms are latent. The pond will also have loopholes and slope collapses due to wind and wave scouring, Rain Water scouring and drilling by various other animals. This requires refurbishment and cleaning of the pond as well as drug disinfection.

The way to repair the fish pond is to drain the water in winter or early spring and let the bottom of the pond freeze in the sun, so that the soil is loose and diseases are reduced. Then, dig out too much mud, repair the dike ridge, fill up the loopholes, and flatten the bottom of the pool. Pond cleaning should be carried out 10 to 15 days before fry restocking, that is, various drugs should be used to kill wild fish, pathogenic bacteria, parasites and other enemy organisms. There are many kinds of drugs in Qingtang, and breeders should choose and apply them according to their own characteristics.

two。 Generally speaking, the fattening water quality is about one week after clearing the pond to before the fry goes into the pond, and the water is injected 40cm to 60cm. Then stack organic fertilizer in a corner of the pond to cultivate palatable natural bait for fish fry so that they can eat enough food after entering the pond, which is especially suitable for the cultivation of Pelteobagrus fulvidraco before 5 cm. The quantity and type of base fertilizer should be adjusted according to local conditions. According to the source of fertilizer, it is mainly divided into two kinds: one is organic manure, such as livestock, poultry and human feces and urine, which is generally applied 6-7 days before the fry goes into the pond, about 300,500 kilograms per mu. However, depending on the fertility of the original ponds, more should be applied in new ponds and sandy ponds, and less in old ponds with thick sediment. The second is big grass green fertilizer, which is generally piled up 7-9 days before the fry goes into the pond, 300 to 400 kilograms per mu. In order to accelerate fertilizer and water, chemical fertilizers can be applied concurrently, generally 5-10 kg of ammonia per mu, or 4 kg of ammonium sulfate, ammonium nitrate, urea and ammonium chloride, and 3-4 kg of calcium superphosphate.

3. Fish fry restocking

1) the identification of the quality of fish fry the quality of fish fry is mainly manifested in whether the physique is strong or not. The fry with good physique are bright in color, fat and uniform in shape, neat in size, and can be seen swimming lively when placed in a white porcelain basin (plate).

2) the stocking density of larvae fresh out of the film in the running pond can be 5000 million fish per cubic meter of water, and when it grows to about 1 cm, the stocking density is 3000 fish per cubic meter, and the stocking density is 3000 fish per cubic meter. 2000 million 3000 fish per cubic meter of water.

3) Culture and stocking density in ponds, as the cultivation conditions in ponds are generally worse than those in running ponds, the stocking density is much less, about 20 to 30 tails per square meter. If the density is too high, the pond conditions and water natural bait can not keep up with the needs of fish fry, so the growth rate is slow. Be careful not to raise other fish fry in fish fry cultivation.

4) the stocking density of yellow croaker fry in cage culture is much higher than that in ponds. However, it must be determined according to the size of the cage, water quality and bait conditions. That is to say, the stocking density varies with the water quality and other factors. In the cages with good water quality and high transparency, the stocking density is higher than that in the cages with low transparency. Generally speaking, it is appropriate to breed and hatch 3000 fish per cubic meter of water, 2000 fish per centimeter and 1500 fish per cubic meter.

4. Bait and feeding yellow croaker fry 0.9 cm long after going into the pond, no bait and a small amount of mixed pellet feed were given a few days ago. Because in the stage before 5cm, Pelteobagrus fulvidraco mainly feeds on zooplankton, chironomid larvae and nauplii, insects, as well as artificial mixed bait, which is generally mixed with powdery fodder. stir it into a ball with water and feed it directly into the fish pond and spread it on the bait table at the bottom of the pond. The reference formula of the compound feed is: fresh fish milk 35%, soybean cake powder 5%, third-class powder 23%, corn meal 15%, adhesive 3%. The water temperature is 20-32 ℃ and fed once a day in the morning and once in the afternoon, accounting for about 3% and 5% of the fish's body weight. According to the group feeding habits of Pelteobagrus fulvidraco, a more centralized feeding method should be adopted, and the feeding area accounts for about 6% to 10% of the pond area.

In the process of feeding, we must adhere to the principle of "four determinations", that is, timing, positioning, quantity and quality. The feeding time and times were set according to the feeding rule of fish fry, and the fixed-point feeding was carried out according to the characteristics of cluster feeding of Pelteobagrus fulvidraco, and the quality and quantity of bait were guaranteed. The feeding amount of Pelteobagrus fulvidraco fry is 5%-7% of body weight, 3-4 times a day, and more in the morning and evening. The specific feeding amount of each time can be determined according to the eating condition and water temperature of Pelteobagrus fulvidraco. The fry can be eaten within 1 hour. The quality of artificial feed or fresh feed should be guaranteed.

5. Matters needing attention in stocking fish fry must pay attention to the following aspects:

The main results are as follows: 1) the fry of Pelteobagrus fulvidraco can enter the pond only when they reach horizontal swimming and active feeding. Getting into the pond too early, the fry's activity ability is weak, the feeding ability is poor, it is difficult to adapt to the new environment of the pond, and it is easy to die.

2) the specifications of fish fry in the lower pond should be neat, otherwise the growth rate of fry will be inconsistent and the size will vary greatly.

3) Fish fry should carry out net-pulling exercise before transportation, eliminate weak fry, increase the survival rate of transportation and improve the quality of fry.

4) if the fry of Pelteobagrus fulvidraco enters the breeding pond directly from the temporary culture pond, it should be fed first and then go down to the breeding pond, which can improve the physique of Pelteobagrus fulvidraco fry and increase the survival rate of the fry.

5) the time of fry entering the pond should be chosen when there is a large number of plankton in the pond, which is difficult to achieve, because the growth and reproduction rate of plankton in the pond is difficult to coincide with that of larvae. Both are greatly affected by external factors such as water temperature.

6) the fish fry should be tested before entering the pond, and the temperature difference between the two should not exceed 2 ℃. If the temperature difference is too large, put the fry bag in the fish pond for half an hour to adjust the temperature difference.

7) when entering the pond, be careful. When releasing the fry, slowly pour out (or put in) the fry along the edge of the pond, and stick your feet to the bottom when moving, so as not to trample on the fry.