Technical measures for early breeding of silver carp along the Huai region
There are many lakes and ditches along the Huaihuai area, and the water resources are relatively abundant, which is an important aquatic product production base in China. In recent years, silver carp and other family fish and splash fry produced in the southern region have been continuously marketed to the north, and the sales market for fish fry produced in the northern region has gradually shrunk, and the sales volume has plummeted. How to breed the four major fish fry early, cope with market changes, and seek living space has become a problem that must be considered by major fish fry production enterprises and aquatic technology promotion departments in the Huaihuai region. Huaiyuan County is located in the middle of the Huai River, is the key excellent fry breeding base in Anhui Province, over the years the author has been discussing and applying the family fish early breeding technology measures, and has achieved remarkable results in production, now the silver carp early breeding technology is summarized as follows:
Fish silver carp, silver carp
First, the conditions of the pond for the parent cultivation of silver carp
The area is 5 to 10 mu, the pond depth is 2.5 m, the water level is maintained 2.0 m during breeding, the east-west direction, the length and width ratio is 2 to 3..1. Close to the water source, fresh water quality, plenty of water. The pond is widened and raised, and the pond is maintained and connected to the production road in the field area, which is convenient for the operation of the net and the entry and exit of fish transport vehicles. The power facilities are complete, equipped with aerators, water pumps, etc. The inlet and drainage channels are unobstructed and relatively independent. There are no tall trees and buildings around the pond to block the light from the wind.
2. Parental cultivation
1. Parental selection
In autumn or spring, silver carp parents are selected from natural lake reservoirs or artificial breeding ponds, requiring good body shape, smooth body surface, harmless and insect-free, and obvious male and female reproductive traits, and the age and growth status of silver carp are inferred through scales and individual size, and silver carp with an age of 5 years or more and a weight of more than 4 kg are selected as parents.
2. Stocking density
15 groups of silver carp parents were stocked per acre of water surface, and the male-female ratio was 1..1.2. At the same time, four bighead carp parents weighing 15 to 20 kg, two grass carp parents weighing 10 kg, and 5 carp with a size of 1 kg were also polycultured. The total stocking amount per mu of water surface shall not exceed 400 kg.
3. Clear the pond
Before parental stocking, use quicklime belt water to clear the pond disinfection, the amount of quicklime is about 150kg per acre of water surface, and it is required to evenly sprinkle the lime slurry that has just reacted with water, and the effect of hot sprinkling is remarkable. The standard of disinfection is to completely kill predators and wild fish in the water.
4. Fertilization and water quality management
Silver carp parent breeding pond uses fertilizer type of organic fertilizer and biological fertilizer, newly excavated pond per acre of water surface using fermented cow manure or chicken manure 200 ~ 350kg, the old pond bottom is more fertile can not be applied bottom fertilizer. In the cultivation process, biological fertilizers and microecological preparations are applied appropriately according to the color of the water. Regularly checking the number and variety of algae in the water body, and using phosphate fertilizer to adjust the nitrogen-phosphorus ratio of the water body, can effectively promote the reproduction of beneficial algae. According to the change of water quality, add water or change water at the right time to increase the dissolved oxygen content of the water. The spring water level is maintained at about 1.5m, which is convenient for cultivating fertilizer water quality and improving the water temperature of the pond, and the production management takes a step-by-step approach to continuously improve the water level, simulate the natural water ecological environment, and use the flowing water to stimulate and effectively promote the early growth and development of silver carp gonads.
In the Huai region every year in mid-April, when the weather is clear, the water temperature rises to about 20 °C. When the water temperature reaches more than 20 ° C, a large amount of flushing is one of the effective measures to promote the rapid development of the parental gonads. The method of draining water while flushing should be adopted to maintain the flow of water, improve the quality of pond water, and prevent hypoxic floating heads of parents before breeding.
Jiangsu Ganyu 260,000 acres of pollution-free freshwater fish catch in large areas
5. Feed feeding
Feed selection silver carp puffed floating full-price compound feed, protein content of about 30%, you can also use self-prepared feed to feed silver carp parents. The ingredient formula is: 15% of soybean cake, 10% of rapeseed cake, 35% of bran, 30% of rice bran, 5% of fishmeal, and 5% of others.
Attaching importance to prenatal feeding management and ensuring the supply of parental nutrition is very critical to the early breeding of silver carp. The first is parental autumn cultivation. Silver carp parents after the last reproductive cycle of its gonads rapidly degenerated to the second stage, before wintering need a lot of nutrients to ensure the smooth development of the gonads to the end of the ii. period or the beginning of the III. period, the main point of autumn feeding is to adhere to late stopping, along the Huai area can be fed until the middle and late November, the water temperature below 10 ° C can not be fed or less feeding. The second is parental spring cultivation. In the spring, the water temperature rises to more than 12 ° C in March, you can start feeding artificial feed, feeding once a day at noon, sprinkling material from the upper air outlet of the pond, 2 to 3 kg each time, and after the silver carp is fed normally, the feeding amount increases to about 5% of the parental body weight. Pay attention to feeding more on sunny days, and less feeding or no feeding in windy and rainy weather. After feeding logistics to observe the feeding status of the fish, find the cause of the problem in time and solve it.
6. Disease prevention and control
In accordance with the principle of "disease-free prevention, early treatment of diseases", we should do a good job in the prevention and control of parental diseases. Once the parents in the breeding are sick, they will seriously affect their gonadal development, and even lead to the failure of parental induction. Give full play to the role of microecological preparations in disease prevention work, regularly use photosynthetic bacteria, bacillus, lactic acid bacteria, yeasts, etc., use a large number of water quality regulators and substrate improvers, minimize the use of other fishing drugs, and eliminate the use of antibiotics to prevent fish diseases. The main diseases of silver carp parents are anchorhead loach disease, printing disease and so on. The pathogen of silver carp anchorhead loach disease is polymorphic anchorhead loach, parasitizing the body surface and gills, and in the early stage of the disease, the fish body appears non-contiguous erythema or red spots, and the parents are susceptible to infection after childbirth. The parental pond is disinfected with potassium permanganate when it is released, which can kill the larvae of anchorhead loach, and the concentration of use is: 10~20mg/kg, and the medicinal bath time is 10~20min. At the beginning of the disease, insecticides such as dimethodium insects were used for early control, and the effect was better, and the concentration of 90% of the crystalline dimethods used to treat anchorhead loach disease was: 0.3 to 0.5mg/kg. Printing disease occurs more often in summer, other seasons have milder incidence, its pathogen is punctate aeromonas, the use of general disinfectants can be prevented and treated, when the parental disease is more severe, take the injection of streptomycin sulfate treatment, the injection amount of 15mg or 2×104IU / kg.
30 pounds of heavy silver carp
3. Artificial breeding
1. Dragnet check
Enter the month of April, choose the sunny weather to drag the net to check the parental development of silver carp. Silver carp is impatient, good at jumping, and it is easy to cause harm to the silver carp parents during inspection, so it is not possible to repeatedly drag the net to check the parents of a pond many times, you can stagger it, do it in mind, and start artificial induction work as soon as possible.
2. Parental selection
There are large differences in the development of individual gonads in different silver carp parents, and in order to ensure the smooth development of early breeding, it is necessary to select better developed parents for artificial induction. Selection criteria: male fish chase the star significantly, light pressure abdomen has semen outflow, semen thick, into the water is scattered; female belly expansion, ovarian contour is obvious, reproductive pore color ruddy, can further use the egg digger to observe the egg maturation status, mature eggs appear as large and full, neat size, diameter greater than 1.1mm, nuclear deviation, yellow-green or bluish-gray.
3. Artificial induction of labor
The water temperature for several consecutive days reached about 20 ° C, the water was flushed for 3 to 4 hours every day, when it was found that the pond silver carp parents were restless and rapidly swimming on the surface of the water body, it showed that the parents developed well, and the male fish had signs of estrus, and artificial induction could be carried out at this time.
HCG, LRH-A2, DOM and other drugs were selected as the parent oxytocin of silver carp, and the chest injection method was adopted, with one injection for males and two injections for females. Specific dose and operation: the first injection of 400 IUHCG + 2 mg LRH-A2 + 1 mgDOM per kilogram of fish body weight, the same drug dose for females and males, and the second injection of female fish at an interval of 6 to 7 h, the drug dose is 800 IU HCG/kg. After the first injection, the male enters the spawning pond, the female enters the recuperation pool, and after the second injection, the female enters the spawning pool and waits to be delivered with the male.
4. Flowing water incubation
The water temperature is 20 °C effect time is about 15h, the eggs are received in time after estrus spawning, and the fertilized eggs are counted and enter the circulation water to hatch. Early water temperature is low, the hatching time of fry will be delayed accordingly, hatching management should pay attention to changes in flow rate, flow rate and water quality. When the fertilized egg is out of the membrane, it is necessary to carefully manage it, brush the filter screen frequently, and remove dirt. The water temperature is 20 to 22 °C, and it takes about 40 h to hatch the fry. After about 70 hours of development, the newly hatched seedlings begin to inflate, the naked eye observes the appearance of waist points, and the fry can swim in parallel in the water and can be reared in the pond.