Another ID thread. Am I in trouble???

[Delphinus]

I've never seen a canary wrasse or radiant wrasse that didn't pretty much eradicate a flatworm population, given enough time. Plus, they are wicked pretty fish worthy of keeping in their own right.

There was a time there you couldn't get Flatworm Exit in Canada due to some kind of legal issue with the labeling or something. Not sure if that's resolved. Ask around, your LFS might still be able to get it, but if it it isn't available then look at mail-order from the U.S. Only thing with a chemical treatment is it can spike your tank with the massive die off so manual removal for as much as possible is a must.

That said ... I have had flatworms on a couple occasions, but tried canary wrasses in both cases and they did the trick within a month or two.

The only cautionary with the wrasses is that they are jumpers and it's probably more a question of when than if. If you have an open top tank you'll need to take countermeasures to ensure you don't find some floor jerky some day.