I haven't treated a Leopard wrasse but I was successful with a rhomboid and fairy wrasse using Copper Power. Both seemed unphased during the treatment.
- I made sure they were acclimated to the qt tank and eating before treatment.
- I added a small amount of copper a day. I think it took me about 4-5 days to get up to the desired dose. Pretty sure this was the key to success.
Using an API kit I played it on the safe side. I didn't want to guess with the rhomboid so I bought the Hanna Checker for copper.
I read about a lot of people having trouble with cupramine and wrasse, not sure how much truth there is to that but I steered clear.