| Salt Yes or No?
This debate seems to go on and on, here are the facts, as I understand them. There are two types of fresh water fish -
Primary freshwater fish -
Secondary freshwater fish Primary freshwater fish evolved in freshwater and have no physiological adaptations to cope with salt. Secondary freshwater fish have ancestors that moved into freshwater from the sea, and adapted to freshwater conditions, this group still retain some ability to cope with salt in their water. Salt has a multitude of uses in the aquarium, treating disease, reducing the toxicity of nitrite and so on. It should not be used routinely in the freshwater aquarium. Some fish that are commonly classed as freshwater fish (some Livebearers), are in fact brackish water fish, and of course these do need salt in the water for their well being. So why do so many people, and so many books recommend it? I think the answer to that comes from the past when the biological process within the filter was poorly understood, and fish were routinely exposed to nitrite in their water. Salt greatly reduces the toxicity of nitrite so fish in aquariums that had salt added would appear to do better than the ones that didn’t. The same argument could also be applied to goldfish kept in a bowl and cleaned out once a week ( the water quality must have been horrendous). Even today I am informed that breeders of Bettas recommend using it, but they keep their males in small unfiltered tanks, so once again there could be a reason why salt appears to help. If you have good water quality in your tank, and you keep only true freshwater fish. You should not add any salt to the water. Not only does it not serve any useful purpose it will lower the Oxygen carrying capacity of the water and it will stress the fish. Back to Beginners Guide | 
