Bignick, you are absolutely right. It only takes one nip and a mild mannered shark could be scarred for life. That's why I thought long and hard before I even added damsels to my system. I didn't want a five dollar fish injuring a five thousand dollar fish. But after a couple of years I wanted more color and movement, and broke down and started adding some fish (after long and careful Qt) I must say though, the emp adds a lot. The big guy is not shy, and swims right up on his side and looks anybody that comes near the lagoon in the eyes, begging for food. I'd bet the thing would look like a football if I wasn't careful how much I feed him. He'll rip the tentacles off the heads of the squid that I feed the sharks, theres no doubt he could cause damage to a sharks eye. I guess what it boils down to is that it is a personal decision how much risk you are willing to take. With my system I was willing to take the risk primarily because I have a lot of room for the fish (200 sq. ft.) I would not have put the fish together in a little 180 or 220. My next decision is, do I put a second and or third emperor in there as well, or would that be pushing it. I would love to have a mated pair of emperor angels, but most pet shops don't or won't ever get a pair.