What kind of lights do you have hooked up to the tank? I personally love the red and white cleaner shrimp commonly found in most reef tanks. (no idea what they are called... I love reef tanks, but I'm still quite inexperienced with salt water) There is one fish I do happen to know the name of which I think are absolutely stunning, but I do know they are hard to care for: green mandarin. I do not know what kind of environment they need nor how big they get, but I frequently read that they are quite tricky to keep. (totally worth it for such a beautiful fish though)