Fruitbat, can the parasite medicine kill the parasite that is already connected to the fish? I thought, and from what I have read, that if it was already attached that it had to be physically removed? BTW
, TOTALLY forgot to mention leeches. I have heard of them before, but haven't actually studied them at all.
Anyways, before treating you should try and remove your fish if you can to a different tank (if you have a different tank that is). The parasites are free swimming little buggers, so there are chances that they could be anywhere I would imagine. A good dose with the medicine, if you follow all of the directions and treat long enough, should get rid of them. In addition to Jungle's Parasite Clear, you can also use Coppersafe by Mardel.
If all else fails, and nothing works, try using Maracide by Mardel. It actually treats the fish, not the water by breaking down the slime coat of your fish, releasing the medicine on your fish's body, and the covering it with a new layer of slime coat. Pretty cool, but kinda strong, can't be used with anything else. Only reason I mention it is if for some reason nothing works, but it will! Okay, enough ranting...
Sounds like your doing good by boiling the rock and stuff, that should kill them all....
I don't see any reason to get new gravel unless you want to and then this would be a good excuse too
Not sure about the snails, but with what ever medicine you choose to use, read and make sure that your snail will be ok, you might have to move it for a while. Ok, Good luck with things, let us know how it goes, and BTW
, welcome to AA!