Sixlinse can be mean. If you're sure, here's a list of the things I'd suggest;
Pretty much any goby whatsoever. If you get a shrimpgoby, add a pistol shrimp. You will not regret it! They're awesome to watch.
Most smaller blennies should be pretty good, just maybe not a lawnmower.
Yellowtail damsel. Careful, you gotta get the right kind. The nice kind of yellowtail damsel is mostly bright blue with a yellow tail, and the yellow extends slightly onto the blue body. Only slightly, though. If it has a yellow belly, it's a yellow-belly devil. The yellowtails are fairly nice, though they flare at some fish and may nip. Usually they'll back away if the other fish so much as looks at them, though, and they aren't any more aggressive than a chromis.
Cardinalfish of some sort, maybe
You could try a few chromis
Cleaner shrimp, maybe
Firefish
Purple firefish
Tilefish
Barnacle blenny
That's just a few. Oh, and get a tuxedo urchin when your algae grows all over, those urchins are only about 3" across at maximum size and have very short, rather dull spines. Their only real downside is, they pick up random small shells and stuff and haul it around as camouflage. They come in blue, pinkish, purple, this pretty black with various speckles, dark red, and a lot of different colors. They aren't sharp at all... You can pick one up, and it just feels like a hairbrush in your hand. They're also great for cleaning algae.