| I had a parasitic isopod on my cleaner and did some research on them. Check out my tank Journal Post 425 (link below). See if those photos are what it looks like. Make sure you read what is in there, I had input from some heavy hitters in the marine world. The bottom line is that if it is a parasitic Isopod, it shouldn't hurt anything else in the tank.
Actually I was told it shouldn't kill the host either, because it relies on the host to keep itself alive. The host is not in any pain from it however more than likely it will not reproduce due to the energy drain. Also the key is that the isopod is specialized to the cleaner shrimp and will not attach to anything else but another cleaner shrimp. | 
