My wife calls me "The Jedi of the Ich Wars"...so listen good young Jedi.
Don't even think of ANYTHING except a proper, timely, and pain-in-the-butt hyposalinity quarantine if you want to GUARANTEE you will be ich free with a new addition. Like was posted above, its not an expensive deal...buy a plain 10 gallon All-glass (6.99) and a heater, and a filter (30 bucks total). Let it cycle like any other tank.
We keep ours at 1.015 salinity, and add new additions to it. Slowly, we lower the salinity to 1.009 over the course of two days. It stays there a month. Don't worry about the fish, he'll be fine, he's alone, the water is clean, and the low salinity makes life easier for a while. After the 30 days, slowly, over a week, bring the salinity back up to match your display tank.
By doing this, you accomplish at least 3 important things:
1) Guarantee no ich, it can't live in there, your fish won't have it.
2) Find out what your new buddy likes to eat, since he's being fed solo, its easy to tell.
3) Get a little assurance that you have a healthy fish. By doing well in the quarantine, and through the quarantine period, you can be certain you have a healthy, hardy fish to add to your main tank, and know for sure he won't be bringing any problems to your other fish.
Its a tough discipline to follow...but think about it. You're going to have the fish for a long, long time if you do things right...isn't a little extra time worth it?
