The logic of many people is very simple. If you want to eat more rice, you will put more rice. Similarly, if the crab production is high, put more seedlings. Based on this thinking, in the past 2015, the purse seine culture in the lake area has increased to more than 1,000 per acre, and the density of Wujin and Changlin in Changzhou, which is represented by high yield, has increased to 2,000 per acre, and even increased to 3,000 in individual regions. More than a mu. How much more can you put in? the answer is negative.
Judging from the output of river crabs in various regions at the end of 2015, most areas did not produce high yields due to high density, but instead reduced production. What are the reasons? It is because everyone does not attach importance to early management and patronizes himself. He ignores the small crabs and the survival rate of crabs is greatly reduced. At this time, someone has to speak, not me. I really don't know how to manage it. How do you manage early and increase the survival rate of crabs? Practice has proved that strengthening nutrition and stabilizing water quality are two key points.
First, strengthen nutrition
Nutrition is a necessary condition for the growth of crab seedlings. In the early stages, the growth rate of nutritional deficiencies will decline, even if the physique is weak, and the anti-stress ability is poor. Often, the clamshell phenomenon such as “pulling feet†and “top shell†does not occur, while the crab seedlings eat. To be full, nutrition is guaranteed. Therefore, it is particularly important to feed and feed your feet early. The specific operation is as follows:
1, artificial feeding. Early feeding is best based on good palatability, such as early opening materials, chilled fish, soybean meal, etc., to ensure normal feeding crabs. When the temperature is low, the deep water area feeds; when the temperature is high, the feeding area can be expanded. Due to the small individuals, poor physical fitness and insufficient digestive capacity, we can artificially add some food attractants and some products for digestive and nutritive health products to improve the digestibility and absorption rate.
2, cultivate natural food. For example, algae, zooplankton, etc. These very good live baits are extremely beneficial to the growth of shrimp and small crabs. So early we need more water to maintain the abundance of algae. The choice of fertilizer and aquatic products is very particular, and it is necessary to select some organic fertilizers that are fully nutritious, well dissolved, easily absorbed, and have high carbon and low nitrogen. Don't mess with fertilizers, because poor quality fertilizers will remain at the bottom of the pond, causing some toxicity such as ammonia nitrogen and nitrous acid to increase.
3. Spill some nutrients in the pond. For example, multi-dimensional amino acid electrolytes, ultra-Vc, nutritional enhancers, complex organic calcium, etc., will also increase the nutritional accumulation of shrimp and crab seedlings, strengthen physical fitness and promote oyster shells. We are familiar with some of the high-yielding regions such as Yixing Xinjian and Jintan Rulin. Some of our better-cultivated customers have poured nutrients every year, especially before and after oyster shells, when early shrimp and crab seedlings have low feed intake and insufficient nutrition. Has played a very good effect.
Second, stable water quality
First, keep deeper. The water level is raised to 60-80 cm or even deeper. Due to the changeable weather in the early days and the large temperature difference between day and night, the temperature of the water will also rise and fall. In this climate, people are prone to catch cold. Not to mention our little crab. In order for them to survive, they still need to maintain a proper depth of water. Water changes in the water temperature will be slower and will give them a time to adapt. The reason is that the water depth is relatively large and the water body is stable. Think of our lake purse seine or shrimps and crabs in rivers and lakes. Heavy winds and heavy rains have little effect on them. Therefore, it is recommended that farming friends deepen the water level early, especially in the past few days will be a substantial cooling, shallow, thin pond crab shrimp seedlings will produce strong stress, can cause serious death.
Second, pay attention to fertilizer. The water and fertilizer ponds are more stable than the water-thin ponds. We need to apply as early as possible to early fertilization and regular fertilization in order to cultivate large-scale algae and high-quality algae. The freshly-fertilized water looks fresh and refreshed due to the small algae. It is tender, but it is very unstable and it is easy to see algae. Regular topdressing can grow algae gradually toward large scale and diversification. The more kinds and types of algae, the more stable the water quality is. The more complex the biological chain in the pond, the more stable the water quality. Sometimes ponds don’t worry too much about insects. Besides it can be used as a high-quality feed for shrimp and crab, it is also a biological chain. In part, some of the pond’s organic matter is destroyed. Insecticides can damage water quality, produce drug residues and poison shrimp seedlings.
Then, reduce man-made damage to water quality. The most common problems in the early days of the crab pond are the problems of moss, leeches, grass filth, and oscillatoria. Many of these bred friends are “very experienced†and take measures to kill them. They are unaware of these killings and algaecides. Some indicators such as beneficial algae, ammonia nitrogen, and nitrite were killed and water quality was destroyed. The resulting drug irritation and excess toxin residues also affect the survival of crab seedlings. Also pay attention to before and after the rain, before and after treatment, pay attention to detoxification and stable water, supplement carbon sources, stabilize water quality, and prevent algae.
In summary, the important measure to improve survival rate in the early stage of crab breeding is to strengthen nutrition and stabilize water quality.
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