I have a razor back musk and a pink belly sideneck in with my sa cichlids. The musk pays no attention whatsoever to the fish. In fact it's common for the fish to swoop in and steal food away from him while he's eating. The sideneck will occasionally chase the fish around the tank but quickly leaves them alone. I am going to move her to a pond where she can have more room to swim, they are very active turtles.
Ime the musk turtles seem to be pretty good with fish, although every turtle is going to be different so be careful. I would never put a res in with fish I cared about.