Greg is totally correct about tangs and why they are so susceptible to external parasites, as well as his remarks about immunity in general.
A while ago I purchased a yellow coris wrasse, didn't quarantine and introduced ich into my tank.
I hooked up the UV
as a prophylactic attempt to contain a big outbreak, started doing 5-10 gallon water changes every 5 days vacuuming the substrate to remove any eggs, and just made sure everyone was fat and happy. In a week spots showed up on a few fish, but only ever 1-3.
What I also noticed during this, or at least it seemed this way, is the cleaner shrimp would seek out the fish that were showing signs of distress, and my flame angel made regular stops by the cleaning station. I even saw the shrimp picking cysts off it, went in with a few spots on his head/fins, came out clean with little blemishes where the cysts were.
pretty cool to watch the little dance the fish and shrimp go through.
!!But cleaner shrimp WILL NOT prevent a big outbreak if other factors are not up to snuff.!!
It's been about 10 days now since I have seen any signs of ich, except for the occasional scratching, but that could be a number of things. If I'm going to have an ongoing issue, I should see more spots in the next couple of days.
So for me at least, the fish are healthy and happy enough to easily fight off any infestation, now to just keep it that way.
I also watch the fish in the store and check the overall health of their complete system.
I just assume that ich is present, haven't been to a store in ages that didn't have a few infected fish, it's how/what they do that I look at.
If I mentioned a sick fish and they take measures to help it right there, that is fine. It's the ones that try to feed you some lame excuse or just shrug it off that don't get my business.
wish more lfs
would quarantine their new stock, but with most offering no type of guarantee, why should they.