This is what I have done successfully now for the past 2 weeks:
Every night I turn the light off for about a half hour then I turn it back on and check all the fish. If there are any isopods on them I do a freshwater dip and the pods
immediately fall off. Although once there was a larger one on the fish that wouldn't let go so I put the fish on a wet paper towel and pulled the @$!! off with a pair of tweezers. The darker the isopod is, the more blood that he's sucked out of your fish. You can see the blood right through their shell(?).
I also did this every morning. In total I've captured and nuked 8 of them. (once I catch one I tend to leave it in the dish and throw it in the microwave for a few minutes. Just my way of getting back. I have not seen any in several days now, so I'm hoping that i got the last of them.