Yes it is good, it helps in many ways but generally only used to aid health issues. eg nitirte in the water as it helps with oxygen transfer in the gills (or something along those lines) Be aware it is different from marine salt.
Just also be aware that it does not evaporate with the water so only re-add salt for the amount of water you take from a water change. It you do top ups then just add the water.
mgk: He said one tablespoon not teaspoon

. One tablespoon is the amount quoted on my salt I use for freashwater.