Salt helps gill function. Helps in the formation of the protective slime coating on the fish, prevention absorption of harmful nitrite. Salt also helps get rid of parasites.
Sometimes, fish which are sick will need to be placed in a Salt Dip. A dosage of two teaspoons to a gallon (4.5 litres) would be ideal. The sick fish may need to be kept in a salt bath for about half an hour.
A salt bath involves adding salt to aquarium itself. This helps in treating your entire stock at the same time. However, this is not possible for all types of aquariums. If your aquarium has live plants, the salt may damage them. Some species of fish do not have scales such as corydoras. These cannot tolerate salt. Some species of tetra fish are also sensitive to salt. Do not use salt if you have such salt-sensitive species of fish.