Not all fish tanks need to be salted after each water change. If freshwater fish are raised, there is no need to add salt to the water. The purpose of adding salt is only to change the osmotic pressure, which is not very helpful to the health of fish. Because the salinity is relatively low, it cannot achieve the effect of sterilization and prevention. If it is marine fish, the general water is specially prepared for seawater, and it is not easy to add salt to change salinity.

1. Reduce the burden on kidneys: After adding salt to the fish tank, the amount of water entering the fish from the outside will decrease due to the change of osmotic pressure. Because freshwater fish need kidneys to drain water, less water enters and less water is discharged, which can reduce the burden on kidneys and is very helpful to the health of fish.

2. Avoid bacterial invasion: After the osmotic pressure changes, bacteria can also be prevented from entering the fish. Generally, after fish get sick, they need to add salt properly, and the salinity should be controlled at about 3/1000. The purpose is not to sterilize, but to prevent bacteria from invading by reducing water entry.

3. Supplementing trace elements: The salt used for fish is generally coarse salt, which contains certain trace elements, which is also helpful to the health of fish and can make it grow better. It should be noted that iodized salt should not be put into water, which is not good.