It is not good to put salt in koi jar. There is no need to put salt in normal fish farming. Salt will increase the osmotic pressure of water body, which is not very helpful to the growth of fish. Moreover, it will lead to the change of salinity in the process of changing water, which makes it difficult to judge the concentration of salt in water, and the fluctuation of water quality will also cause discomfort of fish. Therefore, salt is needed only when fish are sick, which can play an auxiliary role in treatment and is very helpful for their recovery.

1 to prevent germs from invading: Usually, salt is needed when fish are sick, but the purpose of salt is not for sterilization, because the concentration of salt is relatively low, which makes it difficult to achieve sterilization effect, but it can improve the osmotic pressure of water, so as to reduce water infiltration into fish and germs.

2. Reduce the burden on kidneys: As mentioned above, salt can change the osmotic pressure, and water will penetrate from places with low osmotic pressure to places with high osmotic pressure, while less water will enter, and less water will need to be discharged by fish, which can reduce the burden on kidneys and help their rehabilitation.

3. Sterilization and disinfection: Although normal salt can't achieve the purpose of sterilization and disinfection, fish can be fished out of the fish tank and soaked in specially prepared salt water. Because of its high concentration, it can play a sterilization effect, but the soaking time should not be too long. If fish are found unwell, they should be put back immediately.