What are the first-aid methods for oxygen deprivation in crayfish?
SummaryExcessive density causes oxygen deprivation: adjust the breeding density in time and turn on the aerator to add oxygen. Overfeeding causes oxygen deprivation: adopt a feeding method with fixed quantity, fixed quality and fixed timing, feeding bait once each morning and afternoon. Excessive waterweed area causes oxygen deprivation: keep the waterweed area controlled between 30%-50%, promptly remove rotting waterweed from the water surface, and ensure the water surface gets sufficient sunlight. Sudden water quality changes cause oxygen deprivation: spread quicklime once every 15 days to maintain water quality.
I. First-aid methods for oxygen deprivation in crayfish
1. Reasonable stocking density
Generally, in a breeding pond dedicated to crayfish, around July-September each year, 60-80 jin of crayfish seedlings can be stocked per mu of breeding pond, with a male-to-female ratio of 3:1; alternatively, 20,000-30,000 juvenile shrimp of 2-4 cm can be stocked in spring.
2. Reasonable bait placement
Crayfish like to come out to forage at night and have the habit of competing for food and overeating. Therefore, when feeding crayfish feed, choose to feed once each morning and afternoon, and adopt a feeding method with fixed quantity, fixed quality and fixed timing; during this period, feed enough and evenly, which is beneficial to the healthy growth of crayfish.
3. Control the waterweed area
The area where waterweed is planted should be controlled between 30%-50%, and it should be dispersed to ensure the water surface of the breeding pond gets sufficient sunlight.
4. Keep the water quality fresh
When stocking crayfish seedlings, ensure the water quality in the breeding pond is sufficiently fresh, and maintain a suitable water level; during the breeding process, spread quicklime once every 15 days.
5. Pay attention to weather changes
If breeding conditions permit, when crayfish suffer oxygen deprivation, turn on the aerator to add oxygen, or splash an appropriate amount of oxygen-increasing agent into the breeding pond.
II. Causes of oxygen deprivation in crayfish
1. Uneven size
When crayfish have been bred in the pond for a relatively long time, adult shrimp from the previous season and shrimp seedlings from the new season coexist at the same time, which easily leads to the strong bullying the weak. At the same time, in order to fully utilize water resources, some farmers also stock fish, crabs and other species in the breeding pond, resulting in high breeding density and causing oxygen deprivation in crayfish.
2. Sudden water quality changes
Farmers who have just started breeding generally worry in the early stage that the crayfish are not getting enough nutrition, so they feed a large amount of bait, or put in a large amount of rapeseed cake after fertilizing, which easily causes the water quality of the breeding pond to become thick. Especially in May-June, when sudden weather changes occur, it can cause oxygen deprivation in crayfish.
3. Overfeeding
In the early stage, in order to promote the growth of crayfish, excessive feeding will make the crayfish eat too full, so they cannot resist low oxygen, which also leads to oxygen deprivation in crayfish.
4. Luxuriant waterweed
If the waterweed in the breeding pond grows luxuriantly, almost the entire pond surface will be covered by waterweed. Some farmers, in order to ensure there is waterweed in the pond during the plum rain season, let the waterweed grow unchecked, which also easily causes oxygen deprivation in crayfish.
5. Rotting waterweed
In summer, the waterweed will die off one after another, or be cut off by crayfish. If it floats in the water and is not removed in time, it will spoil the water quality and cause oxygen deprivation in crayfish.