[They eat a couple of algeas bryopsis and Cheato for sure. They are also known to eat derbesia (hair algea) and a few others but usually only if they others aren't available. In other words it tends to be their least preferred.
[I had one. Really neat little guy, managed to live about 24 hours before he dissapeard. Found him in my sump a day later. Put him back in the tank, another 24 hours dissapeared never to be seen again. :taz:]