+1 tail spot blenny, I really like mine. Saw that others suggested a pair clownfish, a yellow corris wrasse and a royal gramma. I have all of these as well. I can vouch for all of those as easy to keep, personable fish. Begging for food by the lid when your near, ect. A yellow wrasse would also be excellent for pest control. Wrasse and gramma took a while to settle in, but all fish in my reef totally ignore my hands in the tank moving coral and stuff around now.