Salt?

[NinjaPirate]

salt also helps build up the slime coat i think and epsom salt is a household water hardener >.< so dont use it unless you really know whats goin on

Epsom salt is one of those things I keep on hand in case of emergency, as it is a life saver when you find yourself with a fish that has serious internal bloating/swelling. I don't ever use it to treat even simple constipation (veggie matter, aka shelled peas, will do the trick nine times out of ten)

It is not something I use often, but it is very useful when needed.