Various stress reactions seriously affect the feeding and growth of aquatic animals, reduce the survival rate, and even cause death.Adding betaine in feed can improve the decrease of aquatic animal food intake under disease or stress state,maintain nutrition intake and alleviate some disease or stress reactions.

Betaine helps salmon resist cold stress below 10℃ and is an ideal feed additive for some fish in winter.The grass carp fry transported by long distance were put into pond A and pond B with the same conditions. 0.3% betaine was added to the grass carp feed in pond A, and no betaine was added to the grass carp feed in pond B. The results showed that the grass carp fry in pond A were active in water and fed quickly, and no fry died.  The fry in pond B intaked feed slowly and the mortality rate was 4.5%, indicating that betaine had an anti-stress effect.  

 As cell infiltration of protective agent, betaine can improve the biological cells to drought, high humidity and high salt tolerance and hypertonic environment,prevent cell and salts into the water erosion, improve cell membrane Na -k pump function, stability of enzyme activity and function of biological macromolecules, then adjust the balance between osmotic pressure and ion,maintain the nutrient absorption function, enhance fish, shrimp and other osmotic pressure shock resistance, improve the survival rate.  

The high concentration of inorganic salts in seawater is not conducive to the growth and survival of fish。 Experiments on carp showed that adding 1.5% betaine/amino acid in bait can reduce the water content in the muscle of freshwater fish, delay the aging of fish, and help to maintain the balance of electrolyte and osmotic pressure when the concentration of inorganic salts in water (such as seawater) increases, so that freshwater fish can successfully transit to seawater environment. Betaine helps Marine organisms to maintain a low salt concentration in the body, continuously replenish water, and play a role in osmotic regulation, so that freshwater fish can adapt to the transition to seawater environment。