Penaeus vannamei is easy to float due to anoxia. How to prevent and control the floating phenomenon of Penaeus vannamei

Under normal circumstances, the activity of shrimp in the water is regular, when swimming, the direction is obvious, the speed is fast, and it is sensitive to stimulation. If prawns swim on the surface of the water, the front end of the head is out of the water (antennae, eyes are out of the water), when swimming, there is no direction (loose swimming, loss of balance), slow response to stimulation, it is the performance of "floating head".

Shrimp culture

First, the signs before the "floating head" of prawns:

1. Cloudy and windless, the climate is muggy, the air pressure is low, and the water in the pond is as calm as a mirror. After dusk, a large number of mosquitoes bite the human body in the shrimp pond.

2. The water temperature is high (more than 32 ℃), and the concentration of dissolved oxygen in water is lower than that of 3PPm.

3. the food intake of prawns decreased suddenly, and the residual bait in the pond increased significantly.

4. the water in the pool is too thick, and a large amount of "moss" skin comes out of the water.

5. The snails climb out of the water, and the prawns lie along the edge and move sluggishly.

Second, the light and heavy marks of the "floating head" of shrimp:

1. Limited to the middle of the pool, light; throughout the pool, heavy

2. After being stimulated, prawns can sink immediately, light, but not sink after alarm, heavy

3. Floating head begins before dawn, light; heavy in the evening or during the day

4. The individual Penaeus vannamei has not appeared on the shallow beach by the pool, light, and a large number of prawns swim randomly on the surface of the water body.

III. Solution measures

1. And time seedlings. In the early stage, more than 8000 shrimp ponds per mu were put on the market after "Lesser Heat" and before "Greater Heat".

2. On days of high temperature and low pressure, turn on the aerator in time and oxygenate for 6-8 hours a day.

3. If there is a change in the pool water, new water should be injected in time.

4. When the air temperature exceeds 35 ℃ and the water temperature exceeds 32 ℃, the pond water layer should be deepened in time, and the deep water should be used to increase the temperature difference.

5. When patrolling the pond in the morning and evening, if sick shrimp or fish are found on the edge of the pond, accompanied by signs of "floating head", bait should be suspended for 1-2 days, and dead fish and shrimp should be fished out in time to change water or add water.

6. For the prawn ponds with moss "pan-skinned" at the bottom, change the water immediately and sprinkle the whole pond after diluting with 300g EM bacteria per mu. All shrimp ponds that are not thoroughly desilted should be sprinkled evenly with a water depth of 1 meter per mu with Bishui'an 200 grams diluted to 250 grams.