Prazi works well for flukes but it takes multiple treatments and is a slow process. I know people don't like to treat in the DT, but after much reading, I treated in my DT and didn't lose a single coral or fish. I had to do a couple of FW dips to get flukes off of the eyes so there wasn't permanent damage. I'd do it again if I dad to.
I don't believe copper does anything for flukes.