Predatory capabilities of Caribbean Rock Mantis

[Stomatopods17]

It shouldn't actively hunt fish, defensively injuring them is a risk that domino effects from mild injury - > infection/health problems and so on, but in general it shouldn't harm much beyond the CUC, if you feed the tank mysis it should join the fish in trying to catch some of it.

I'd avoid spot feeding it krill if there's a possibility fish will attempt to get close to steal it, feed everything together.