Masked gobies, Coryphopterus personatus, are small, schooling gobies from Florida that are commonly found around coral heads in deeper water.  The picture isn't so hot, but they are a cool little goby that do very well in a reef tank.  They are a clear pink color and get about an inch and a half long, but are usually around 1.00 inches.  At night they disappear into holes in the rocks, but during the day they hover over the rocks and corals and several of them in a tank add a nice reef look to the tank.  They are real easy to care for and will readily eat most marine flake food and small pellets.  I've kept them in my reef tank and they don't bother any other fish or invertebrates, but because they are small, they may get eaten by bigger fish.  If you've got a reef tank with just small fish, or a nano tank with smaller fish, these guys will be a great addition.