? Since 1988, Penaeus vannamei culture has been popularized in China for nearly 30 years. In the past 30 years, shrimp culture has cooled from the peak to the current aquaculture market. What is the problem that makes some farmers "talk about shrimp discoloration"? What do most people think is the reason why Penaeus vannamei is becoming more and more difficult to raise? Based on the transformation of shrimp culture mode in Shaoxing, Xiaoshan, Zhejiang;

In this process of ups and downs, from the pursuit of change to the courage to innovate and then return to the traditional model. Generally speaking, all changes are inseparable from the profitability of aquaculture. In fact, judging from the whole market at present, no matter what kind of breeding mode, the demand for fry has long been the biggest demand of farmers. With good fry, good aquaculture management is equally important!

In this context, taking shrimp culture in Xiaoshao area of Zhejiang Province in recent two years as an example, we can see whether shrimp seedlings were cared for like babies before and after we released them, and whether there were any management omissions in the years of culture.

Five common factors affecting shrimp seedlings in seedling management

1, water temperature?

① Hazards of low-temperature seedling release: When seedlings are released below 20℃, the seedlings will be directly anorexic, consuming the energy of resisting low temperature in the liver, resulting in delayed development and hindered growth.

(2) Hazard of releasing seedlings when the water temperature is too high: When releasing seedlings, the water temperature is more than 5℃ higher than the water temperature in the seedling bag, which will instantly cause the permeability obstacle of the muscle epidermis of prawns, which is often called blister disease. Seriously, it will directly lead to death, and even slightly increase the chance of secondary bacterial infection in the later stage.

2. salinity?

Salinity is a measure of osmotic pressure, and sodium and potassium ions in water are the key to maintain osmotic pressure.

② Salinity adjustment is to make seedlings adapt to the environment better. Reasonable salinity can minimize the damage caused by seedling release, and the seedlings recover quickly after seedling release.

3. Heavy metals?

① Heavy metals generally refer to metals with specific gravity greater than 5. Excessive heavy metals will cause serious pollution to the water body, which is one of the toxic substances in the water body.

(2) Especially the gill and digestive tract of shrimp seedlings such as chromium were corroded and destroyed.

4. Ammonia nitrogen?

① The high concentration of molecular ammonia leads to the direct poisoning death of shrimp seedlings, which is characterized by necrosis of epidermal tissue and loss of oxygen-carrying function of blood.

② Long-term low concentration will slowly corrode epidermal mucosal cells and cause tissue dysfunction, such as chronic hypoxia caused by gill injury and chronic toxic enteritis caused by intestinal injury.

(3) Even if the long-term low concentration (exceeding the standard) does not cause early death, it will also affect the growth and development, and the later resistance is also poor.

5. Residual chlorine?

① Strong irritation, serious damage to gills, and easy to generate carcinogenic and mutagenic toxic substances such as chloroform and chloroform with organic substances in water.

② It will affect the normal reproduction of aquatic microorganisms such as bacteria and algae, and affect the early water quality. Especially the pond is disinfected with bleaching powder, so there will be some residual chlorine after disinfection. It should be noted that the bottom water sample must be taken when detecting residual chlorine, otherwise it will be inaccurate.