dirtyblacksocks;1947989; said:Common table salt is the same as aquarium salt - just watch for additives, like everyone else said.
Epsom salt can also be used as a general laxative to help cure blockages in your fish - which is a more common problem in smaller fish than larger ones.
More info:
Table salt is processed with magnesium carbonate, sodium iodide, potassium iodide, and potassium iodate. Aquarium salt is mined Rock Salt (also called Halite).
Epsom salt is Magnesium Sulfate. When adding it with aquarium salt, you create brackish water. This completes the four major ions in sea water.