River crab aquaculture is usually carried out in paddy fields. In order to improve the survival rate of aquaculture and achieve good economic benefits, temporary culture is very critical.
1. Preparation of temporary pond
The best temporary pond is 1 mu of land, and it can be bigger if the conditions are suitable. The temporary pond is required not to apply pesticides (especially organic phosphorus herbicides), as far as possible, do not apply or less fertilizer (diamine, sulfur ammonia, bicarbonate of ammonia and other prohibited inputs). In 20 days before the release of seedlings can be applied to a certain amount of organic fertilizer such as rotting chicken manure 150 kg ~ 250 kg or the appropriate amount (according to the original amount of half or less) urea, into the seedling can not be applied again.
Inlet and drainage are self-contained, and the inlet and outlet are set diagonally. The depth of water on the beach surface is kept at 20 centimeters. Pool dug around the ring ditch, ditch width of about 100 cm, ditch depth of 40 cm ~ 50 cm, slope ratio of 1:2. set up escape is very important, the pool around the best use of mesh plus plastic film in the form of set up escape, which is characterized by the flood season can be flood control and to prevent the escape of crab seedlings.
Disinfection and decontamination, temporary pool in the release of seedlings before half a month to use quicklime or bleach for disinfection. Into the water 10 cm, according to the concentration, that is, quicklime 50 kg / mu ~ 75 kg / mu or bleach 2 kg / mu ~ 7 kg / mu, seedling field disinfection medication can be reduced to 1/10, will be converted to water into a slurry of the whole pool evenly sprinkled. Can also be combined with the application of organic fertilizers, that is, lime mixed into chicken manure in the plowing spin into the pool. In addition, frogs, rats, snakes and other natural enemies of these crab seedlings, should be taken outside the pool under the rodenticide, manpower to capture a variety of ways to remove it as thoroughly as possible.
Transplanting water plants, where possible, water hyacinth, floating weeds or other water weeds into the ring ditch, it is best to cover all the ring ditch.
2. temporary density
Earth pool ecological seedlings to put 0.5 kilograms to 1 kilogram per mu is appropriate, preferably 0.5 kilograms per mu. If conditions are limited, you can also increase the density of temporary rearing, but it is best not to exceed 2 kg / mu. If the density is high, the pool must be divided in advance.
3.Crab seedling stocking
(1)Preparation before stockingThe water depth of the temporary stocking pond shall not be less than 20cm, and it is better to change the water thoroughly for 2 to 3 times before stocking. Ammonia nitrogen in the temporary rearing pool water should not be higher than 2mg/liter, high ammonia nitrogen will lead to the destruction of all crab seedlings, if this phenomenon must take measures to deal with before the release of seedlings. (2)Release the seedling in the upwind place, multi-point seedling, do not put the seedling box upside down seedling.
4. Baiting management
(1)The baiting pond should be kept with a certain number of branchiostoma (commonly known as water lice). If you can keep about 20 water lice around a crab fry, you can skip baiting during the staging period. If the amount of water lice is insufficient, they can be moved in from elsewhere. Fresh animal bait, such as mashed minced fish, can also be fed in moderation. Each kilogram of seedlings can be fed 1 kg to 2 kg of material per day, small amounts of multiple, uniform feeding. At the beginning of the day 6 times to 8 times, and then gradually reduced. Feeding adhere to the principle of "observation feeding", that is, 2 hours after the bait, see whether the bait is left, and then increase or decrease the amount of bait as appropriate.
(2) water change seedling just into the pool 2 days ~ 3 days as far as possible do not change the water (under normal water quality), until the big eye larvae successfully molt for a period of baby crabs, and then appropriate amount of water change, each time the amount of water change in the 1 / 3 ~ 1/4. Requirement of water for the freshwater pollution-free water quality should be fresh. Be careful not to let the water with residual pesticides into the pool, water change is best in the morning around 10 o'clock.
(3) Pool patrols adhere to the daily morning and evening patrols once (excluding baiting observations), mainly to see whether the crab seedling activity is normal, the water quality has no change, anti-escape and the inlet and outlet have no loopholes, especially in rainy days should pay more attention to the observation, found that the problem is dealt with in a timely manner.