False clown fish

Wikipedia: "One can differentiate between Percula (true) and Ocellaris (false) by their respective colors and patterns. Ocellaris are usually less vibrantly colored, and have 11 dorsal fin-spines instead of 10, as on the Percula. Also, the species have different eye arrangements: Percula have bright orange irises, making their eyes appear smaller, whereas Ocellaris have grey/orange irises which make the species eyes appear bigger." Percula also have broader black lines in its pattern. (according to an aquarist friend of mine)