In July, the high temperature season approached. According to meteorological department forecasts, the average temperature of crab farming areas in Anhui, Hubei, and Hubei is approximately 30°C. High-temperature weather above 35°C will occur in mid-late and late mid-term, and monthly precipitation will be normal. Or normal more than the main, about 160-180mm (perennial 173.2mm). Crab aquaculture has been in a critical period. The adaptability of various biological factors in the water body to the environment is very different, the water environment changes rapidly, the growth conditions of various types of aquatic plants are also different, the speed of nutritive salt reaction is accelerated, and fish, shrimp and crab grow in crab ponds. Each has its own characteristics. Therefore, the management of crab ponds has new requirements and new features.
First, bait feeding and water quality management
To July, crab ponds generally have more than 70 pounds of crabs, shrimps, and fish ponds. Therefore, according to 8-10% of the amount of bait, the amount of bait per mu should be 5-7 pounds. During the high temperature period, the composition of the bait was adjusted. The animal-based bait was mainly used in the early period and changed to 50% for animals and plants. The bait should be observed after feeding and the bait should be put into the crab pool for 4-6 hours. After eating, excessive feeding of bait will cause deterioration of water quality. If there are leftover bait, it should be analyzed whether the weather is the cause of the weather or the water quality. If the water is cloudy or the grass is heavily contaminated, the feed may be insufficient and the amount of feed should be increased. It is suggested that the feeding amount of small fish during the high temperature period should be controlled at about 3 pounds/mu, which will help improve the water environment. In July, the water quality of crab ponds should be controlled at an average water depth of 60cm or more. By the end of July, the water level should be increased to the highest level. In water quality regulation, groundwater must be added and water must be added within 2-3 days. The water quality should be kept cool and lively. The transparency of water quality should be kept above 50cm. During the high temperature period, crab ponds often suffer from poor water quality, water stratification, deterioration of water quality in deep trenches, poor water quality in local bushes, and eutrophication of water bodies. Therefore, in addition to regular water and water changes, water quality should be maintained. Substrate improvers and microbial preparations, and can detoxify the water body, improve the bottom quality and water quality, use it once every 10 days or so, the environment of crab pond water is poor, and it is used once every 7 days.
II. Pond Environment Improvement and Disease Prevention and Control
In July, Vallisneria alterniflora, Hydrilla verticillata and Ceratophyllum albopictus were still in a vigorous growth stage, creating a good habitat for crab growth and oyster shells, and played an effective role in purifying water quality, cooling water bodies, and increasing dissolved oxygen in water bodies. The aquatic plants in the crab pool should be well protected. If it is found that the aquatic plants are heavily contaminated or the water is turbid, measures should be taken in time, such as putting in large quantities of high-quality snails, and feeding bait to prevent batting. In order to observe and diligently handle groundwater, we must remove the remaining floating plants in time, and gradually eliminate the Elodea that have not yet been removed at the bottom of the trenches to keep the crab ponds clean and hygienic, and prevent the plants from rotting and damaging the sediments and water quality. Caused deterioration of the pond environment.
In terms of disease prevention and control, it is necessary to prevent disease and prevent disease. Dirt modifiers and microbial preparations should be used at the present stage. Microecological preparations should be used to multiply beneficial microorganisms in water bodies and become a dominant population in the microbial system of the aquaculture water environment. Through its metabolism, it can improve water quality and inhibit harmful bacteria. Reproduction reduces the incidence of disease. At the same time, it is now possible to add oral medicine and vitamins, minerals and other additives to the bait to improve the disease resistance of the crab. After the fourth oyster shell was basically completed, the mineral elements, nutrients, and vitamins in the pond were greatly absorbed and utilized by the crabs. In order to ensure the healthy growth of the crabs in the pond and ensure the smooth progress of the fifth oyster shell of the crabs, it is recommended that Farmers Quantang splash hard shell Bao and multidimensional nutrition additives 1-2 times, in addition to some early insecticidal disinfection crab ponds can choose to rain over the sky, the water temperature is not high and the crab is not the moment when the overall vitality of bulk casualties A caterpillar-killing drug and low-dose quicklime shall be splashed, and lime shall be sprayed in an amount of 5-10 pounds per metre of water per metre of rice to ensure that there are no large numbers of parasites on the body surface and pupa of the crab in the high-temperature season and the water body is refreshed. The current disease prevention and control work Should be combined with feed optimization feeding, environmental improvement and other work carried out, and effectively prevent diseases and health breeding.
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