Fish Med's?

[Kabong]

Maybe I've been reading to much on RC, But I got some wild clowns coming.
Now from the reading on there I should treat the fish before they even show any symptoms.
Well thats not really the way I like too do things, But I wouldn't mind knowing which meds to have on hand just in case.
So from my reading the two i need to keep an eye out for are brook and internal parasites.
Now for the brook I read I should use a formalin treatment. Which I haven't been able to find.
So I'm presuming its not available in Canada.
For the parasites it was also some other treatment Ive never seen available.
So the question is what have you guys used in the past to treat these two, and what were the end results.