The time of stocking of crab fry, what should be paid attention to before stocking?

The time of stocking crab seedlings: March to May is the suitable time to release crab fry. Matters needing attention for stocking crab seedlings: choose to release crab seedlings in sunny weather, stable climate and little temperature change, the water level should be kept around 80cm, and the water quality should be "old water". Before stocking, crab seedlings should be put into potassium permanganate or disinfected in an aqueous solution container of anti-stress reaction drugs.

1. Time for stocking crab fry

The period from March to May in spring is the time for concentrated release of crab seedlings in the south and north, during which the packaging, transportation and stocking of crab seedlings are the prerequisite for the recapture rate, stable and high yield of finished crabs.

II. Matters needing attention in packing and transportation of crab seedlings

1. When the crab seedlings pull the net from the overwintering pond, it is necessary to clean the mud in the body of the crab seedlings, maintain the moisture of the Gill filaments of the crab seedlings, and prevent the blockage of water holes and gills from affecting the normal respiration.

2. After raising the net, the crab seedlings should not be in the state of sun exposure and ventilation to avoid Gill moisture evaporation and seedling wilting.

3. The incubator should be empty except for the lid, keep the air permeability inside and outside the box, the crab seedlings in the box should not be crowded, and the ice lollipop without water leakage should be used for refrigeration. According to the length of transportation time, the amount of popsicle and oxygen should be added or reduced appropriately.

4. Keep the incubator hibernating for about 4 ℃, and there is enough oxygen, and then the tape seals the incubator cover. When loading, there should be a proper gap between the pallets and proper ventilation in the insulated compartment. in addition, several cases of ice seal can be installed for backup.

5. If the crab seedlings are transported continuously for more than 24 hours, the survival rate of the crab seedlings needs to be sampled. If there are casualties, the specific reasons need to be investigated item by item according to ventilation, temperature, and transportation time.

Matters needing attention in stocking crab fry

1. Weather

It is necessary to choose to release crab seedlings in the weather with sunny weather, stable climate and little temperature change, so as to prevent a large number of crab seedlings from escaping ashore on the same day, affecting the survival rate of crab seedlings.

2. Water level

The period from March to May is suitable for releasing crab seedlings. Due to the large temperature difference between day and night, crab seedlings are easily stimulated, so the pond water level of crab seedlings should be kept at about 80cm, which is helpful to reduce the stimulation of temperature difference to crab seedlings.

3. Water quality

The water quality of stocking crab seedlings is "old water". Because the algae phase and bacterial phase of the old water are stable, the change is small, and the oxygen production is rich, it can make the crab seedlings adapt to their living environment as soon as possible after entering the pond, which is beneficial to improve the survival rate. at the same time, the pond water polluted by civil sewage, chemical water and pesticide residues can not release crab seedlings.

4. Seedling releasing method

When the crab seedlings go down the pond, you need to take the correct stocking method, commonly known as "disinfection and spitting" method, that is, first put the crab seedlings into an aqueous solution container with certain potassium permanganate or anti-stress reaction drugs for 1-2 minutes and then take them out. Wait 3-5 minutes and put it back in again, 3 times in a row, each time the interval is increased by 2 minutes.