Just don't want it to grow, OR WORSE - infect the easily ich-magnet tang species.
Being an "ich magnet" is a factor of stress and nutrition.....ich (or something else) comes when there's a problem with stress or nutrition. (And yes, Hippo's do have higher requirements for low stress and nutrition than many other fish.)
I'm going to be safe and run dt fallow and keep them in qt. Only true way to achieve peace of mind & ensure ich free, right?
No. Treatments are rife with uncertainty. Just look over the posting history in the Disease forum and you can see failed QT's, TTM, fallow and other treatments more or less all the time.
And it's not only the processes that are failure-prone (human error and otherwise) but the organisms themselves are a problem.
We never, never, never get positive ID on what we're treating, so there's very often a pretty good chance that we've just picked the wrong medication, or the wrong dosage or the wrong treatment process for what we're treating. Being told
XX days for fallow is a great example. There is no
XX days...it's an average or a favorite number and no more. Meaning that there are strains of ich that need nowhere close to 76 days and strains that require more than 76 days....plus temperature and other factors are at work which we don't understand.
Having healthy fish with healthy immune systems is the only way to achieve peace of mind.
If you lack healthy fish with healthy immune systems, then there's room for just about any disease organism – whether parasite, bacteria, virus or otherwise – to make a home. Ich will be far from your only worry, and you'll have to worry each and every time you add something to your tank.
And just to repeat, this is a function (or side-effect) of the state of stress and nutrition you maintain.
For example: If a 10 Gallon QT tank is, hypothetically, too small for the kind of fish, or amount of fish, you have in there, then it's not a good place for QT as the residents will be under a brand new stress the whole time they are in QT on top of whatever was going on to begin with. Having something like ich come up
becomes more likely, not less, since their immune systems may continue to degrade in the cramped quarters.
Another example: A typical diet of dried or processed frozen food does very little to aid the fish's recovery or boost their immune system. Soak dry foods with some fish oil (like you'd take for your health) if dry food is all you can get. Using live or whole-frozen foods is more ideal. Or food with probiotics added, at least.
Hopefully those examples don't apply to your scenario, but they still help transmit the ideas that I'm talking about.
(But if they do, be sure to make some changes!)
My understanding is the parasite is now irritated w/ the copper, and in return irritating the clown.
I don't know how likely, or possible, what you describe is but I wouldn't assume too much in that direction. Copper can be very stressful on fish, and that's not theoretical.
Try to give this guide a look:
FA165/FA165: Use of Copper in Marine Aquaculture and Aquarium
If you aren't testing for the levels of copper in the tank, you should.
