The response of Penaeus vannamei to the changed environmental factors is called "stress response", and the mutation of various physical and chemical indexes in the water are all stress factors. When shrimps respond to the changes of environmental factors, their immune ability will be reduced and a lot of physical energy will be consumed; If the change range of stress factors is not large and the time is not long, shrimp can cope with it and will not cause great harm; On the contrary, if the stress time is too long, the change is large, beyond the adaptability of shrimp, shrimp will get sick or even die.

Ⅰ. The symptoms of shrimp stress reaction were as follows

1. Red beard, red tail fan and red body of shrimp (commonly known as stress red body);

2. Sharply reduce material, even do not eat material, swim along the pool

3. It's very easy to jump into the pond

4. Yellow gills, black gills and broken whiskers are easy to appear.

Ⅱ、 The causes of stress response of prawn were as follows:

1. Algae phase mutation: such as sudden death of algae, clear water color or algae overgrowth, and too thick water color;

2. Climate change, such as severe climate effects such as cold air, typhoon, continuous rainfall, rainstorm, cloudy day, large temperature difference between cold and hot: rainstorm and continuous rainfall will make rainwater gather on the surface of shrimp pond. After rain, the surface water temperature is lower and the bottom water temperature is higher, which causes water convection, and a large number of photosynthesis algae die (water changes) due to lack of photosynthesis algae. In this state, water experience severe hypoxia; The micro ecological balance of water body is broken, and harmful microorganisms propagate in large quantities (water becomes white and turbid), which easily causes the organic matter at the bottom of the pond to decompose and produce hydrogen sulfide and nitrite in the anaerobic state and form accumulation, which will cause the poisoning and death of shrimp.

3. The mutation of physical and chemical indexes in water body: the mutation of water temperature, transparency, pH value, ammonia nitrogen, nitrite, hydrogen sulfide and other indicators will also cause the prawn to produce stress response.

4. Solar term replacement: due to the change of solar terms, unpredictable climate, large temperature difference and uncertain wind direction, the change lasts for a long time, which causes the physical and chemical factors of shrimp water body to change dramatically, which causes the strong stress of prawn to cause virus outbreak and large-scale pond drainage.

5. The use of stimulative insecticides, algal drugs such as copper sulfate, zinc sulfate, or chlorine containing disinfectants can bring strong stress response to prawn.

Ⅲ、 Prevention and treatment of stress reaction

1. Water quality and sediment should be improved frequently to prevent water diversion;

Supplement of carbon source can improve water quality and prevent algae falling.

2. In case of strong wind, rainstorm, thunderstorm, rainy day, northerly wind and other bad weather, nutrition should be added to the water body in time to prevent the occurrence of stress reaction;

3. The amount of water supplement should not be too large, generally about 250px is appropriate. Anti stress products can be used to alleviate the stress reaction;

4. Pay close attention to the weather change frequently, and use anti stress products to adjust the water quality in time.

5. After a large amount of shelling, prawns should be supplemented with calcium in time to make them hard shelled quickly and reduce stress reaction.