It may return whenever he stresses excessively, but see if he'll take to the Formula One Sinking Pellets With Garlic. I tend to think of ich as the common cold, and am always distressed to see somebody lose a whole tank to the pest. I avoid ich-prone species like tangs [my tank's too small, anyway] and I haven't lost a fish to it in---oh, two decades---though I've had it break out, even this year. It's just really hard to avoid having it get into the tank unless you qt even your inverts, because imho it's just apt to get through on your hand or in your net when you bring in a new specimen---or a bag of cheato---from your lfs, so I despair of ever getting an ich-free tank. My favorite fish [gobies, blennies, dragonettes, dartfish] are highly resistent to it, and that's one reason I have a pretty healthy tank. Water params, absolutely fanatic attention to alkalinity level [avoiding skin and gill irritation], and faithful water changes will go a long way to protect the fish. I always keep a couple of what I call 'bellwether' species of corals that alert me to alkalinity and calcium levels just by their behavior: frogspawn is a good one, and certain discosoma mushrooms are good at it. I have a theory that wandering alkalinity levels are one thing that lets it take hold; and I ask myself, well, if the stuff can only live 6 weeks without a host and you haven't had an outbreak in two years, how ich-loaded can your tank be?
This tank is new, and it's already had one specimen bestow it on the tank, but nothing has turned up since he ate a piece of my frogspawn and made a trip back to the lfs. All is quiet and ichless.
If I had tangs or angels I'd be quarantining, no question: they're so susceptible, and they get it so lethally. But mostly if I ever do see it on my tough little guys, I'll head for the Formula One pellets and fully expect it to be gone in 48 hours.
I hope you have similar good luck with your fellow!
