i think 10 would be perfect for a single percula clown. it definitely has more floor space than eclipse 6 and also does not take up much space.......a perfect desktop tank.....I've kept ocellaris clown in 10 (Eclipse 1 w/ a retrofitted lighting system) for more than 3 years, and she's been doing really well....she hasn't grown a lot, but she is happier than ever!........as long as you pay close attention to water quality......should be fine...btw, welcome to the world of saltwater fish!!