Yeah guppy, you're right, most Ich treatments can work in either salt or freshwater. But also rkc772, like guppy said there is more than one strain of ich, and though the general meds kill off most of the infections, such as our antibiotics do, some strains arent even phased by it. Also, if you are noticing heavy damage to your fish's fins, you may be dealing with another organism all together, called fin-rot. Though it's possile ich could still be the cause, your fish would have to be heavily infested, for a long period of time for the flesh to peel away, and the fins to rot. This is because, like many other organisms, they feed off the nutrients in the cells of the fleshy parts of the fish. Typically though, most fish would die before it got to the point of rotting flesh. You may want to do some serious research on common fish diseases before you continue. If you are treating them for Ich, and they have fin-rot, gill-rot, or some other problem, you won't be helping the situation. The bad part though, is that it is a high possibility your tank could be infested with both!!! Don't freak out though, everyone deals with these critters sooner or later, and there is a ton of info. available on the net. But like guppy said, don't up and change the meds half way through, they contain different ingredients, and just because one med claims to be safe on all fish, the other may not be. Plus, it is just a general medication for a general disease. Just like some people are allergic to penuts and others aren't, some fish may not be able to handle a "safe" medication, while others are fine with it. Keep your fish in a holding tank, treat them with your chosen meds., and do water changes on your main tank, raise the salinity, and temp, and get your parameters back in check. Like i said before, all meds., good or bad will lower your water quality, so an already sick fish trying to fight for life in bad water is 10x's harder. It really is a double edged sword, you just have to weigh your pro's and con's of the situation.
--Emi
--Emi