Improving the survival rate of fish fry is the concern of every breeder. The survival of fish fry is not only related to the benefit of this breeding, but also related to the rhythm of breeding throughout the year.
So, how can we effectively improve the survival rate of fish fry? This article will give you a detailed answer.
First, choose the right fry
About this part of the content we in the previous article "How to choose high-quality fish fry? Select the door to see here!" Have done a detailed explanation, this time not to elaborate.
A brief overview is the following 3 points:
1. Carefully select suppliers, including inspection of supplier qualifications, on-site inspection to understand the production environment of fish, and inquiry of breeding technology and parent fish sources.
2. Observe the situation of fish fry, including appearance inspection, vitality test, and check the group consistency.
3. Pay attention to the situation before, during and after transportation.
Second, prepare the fry before entering the pond
Fish fry should be prepared 20 days before entering the pond, the purpose of this step is to clean the pond, disinfect and nourish the water.
1. Drying ponds for dredging
About 20 days before the fry, it is necessary to desilting the pond, remove too much silt after sun exposure or freezing, only retain 15 to 20 cm thick silt, thoroughly remove weeds, sediment and residual organic matter, fully dry the bottom soil of the pond, kill latent harmful bacteria and parasites.
2. Disinfection and purification
Start disinfection within 5 to 7 days after the end of the tanning pond, and evenly spread disinfectants such as quicklime or bleach powder in the pond. The specific amount needs to be flexibly adjusted according to the pond situation, in general, the amount of bleach powder per acre is 15-20 kg, and the amount of quick lime per acre is 100-150 kg.
3. Water injection
2-3 days after disinfection, clean water can be injected into the pond, and the water depth is generally maintained between 1.5 and 2 meters. According to the water quality, fertilizer or microbial preparations can be added appropriately to promote the reproduction of plankton and beneficial bacteria, thereby improving the fertility and stability of the water body.
4. Test the water
1 to 2 days before the fry is released, the water body needs to be fully tested and adjusted. The detection indexes include water temperature, pH value, dissolved oxygen, ammonia nitrogen and nitrite.
The ideal water temperature range should be between 15 and 30 ° C, the pH value should be maintained between 7.2 and 8.5, the dissolved oxygen content should be above 5 mg/l, and the concentration of ammonia nitrogen and nitrite should be controlled below 0.05 mg/l.
Before seeding, check whether the residual drugs in the pond have been completely dissolved and whether the toxicity has disappeared. This can be done by taking the bottom water and placing it in the fry to observe or by using a small cage test.
Three, fry throwing skills
1. Choose the right time and place
Try to choose sunny noon or afternoon seedlings, when the water temperature is high and dissolved oxygen is sufficient, which is conducive to the resumption of fish fry activities.
Put seedlings in the open wind to prevent the fish from being blown ashore.
2. Slow temperature adaptation
When seedlings are placed, the temperature difference between the water temperature in the seedling bag and the pool water is required to be no more than 2 ° C, and the fry can be placed after the seedling bag is placed in the pool for half an hour to avoid temperature difference stress.
3. Pay attention to the delivery method
Tilt the container of fry slowly into the water, so that fry slowly swim out, or pull the container of fry slowly back to avoid sudden pouring into the pool and causing fry injury. And try to disperse into different locations to avoid aggregation or deposition of fish fry.
Iv. Daily breeding management
1. Timely feeding
The feeding of fish fry should be determined according to the size and variety, such as poor feeding capacity of water flower, can be fed egg yolk or soy milk or powder, feeding 6-8 meals a day.
The cultivation is mainly by feeding bait, supplemented by fertilization. 5 days after the fish fry into the tank, in addition to pouring soy milk, powder, but also need to add soybean residue, soybean cake batter. When the water quality becomes clear and the natural food is insufficient, topdressing should be done in time. Of course, attention should also be paid to prevent the water from being too fertilized and to avoid plankton blooms causing flooding.
2. Regular pond patrol
The number of pond patrols should be frequent, and each pond patrol should carefully observe the water quality, the activity and growth of fish, and timely treatment should be found for diseases, and the dead fish should be removed.
3. Prevent fish disease
After the fish fry under the pool to do a good job of parasite prevention and the emergence of bubble disease, which is easy to encounter after the pool two situations.
Parasites have wheel worm, dactylogyrus, etc., this can be treated with corresponding agents, and the probability of general disinfection will be much smaller.
The bubble disease is caused by more factors, such as more dissolved oxygen in the water, the fry will increase the incidence of bubble disease, and if ammonia nitrogen is high, the tail position may also cause bubble disease, and drugs such as noramine have a certain preventive effect for this.
4. Divide the pool timely
After 20 to 25 days of breeding, when the body length is more than 3 cm, it is necessary to time the pool to reduce the density of the pool and promote the growth of the fry.
V. Other precautions
1. Disinfection and anti-stress treatment
The fry may be damaged during transportation, and the body is weak, the anti-stress ability of the body is reduced, and it is easy to be infected with pathogenic microorganisms. Therefore, disinfection and anti-stress treatment should be done before planting.
2. Guard against natural enemies
A few days before the fish fry into the pool to pull the net, to ensure that the aquaculture water enemy organisms have been completely removed, in order to put the seedlings.
3. Feed properly
Within 30 days after seeding, eat less and eat more meals, and try to feed evenly along the edge of the whole pool to ensure that the fry feed evenly and feed enough food.