I wouldn't really go the route of having anything that will eat any beneficial creatures in your fuge, like seahorses. They eat pods and you want those in your fuge. I would go the route of having a really cool stocklist of inverts, like lots of ornametal shrimps and different types of snails, some colorful mushrooms, maybe some feather dusters......a bunch of different kinds of colors, to help clean out stuff floating in the tank, and they lots of different macroalgaes, like chaeto, caulerpa, and some gracilaria (sp?). It would be very beautiful.....and then once the top is covered in chaeto and it is lower light, you could get some sponges.......it would be very colorful and functional. For a fish though, you could add a lawnmower blenny to eat the algae on the rocks. Let it mature for a while and you won't even have to feed him except for maybe a spirulina pellet a couple times a week to supplement.