Some say the "eyes" have it. Perculas quite often have have a pure bright orange iris around the black pupil. This often gives them the illusion of having smaller eyes, or a beady little eyed look, as some say. Ocellaris clowns more often have a grayish orange iris which gives them the illusion of a larger looking eye than some percula clownfish. But, this sign isn't always reliable. Percula clownfish more often than not have more black coloration on their bodies than the similar looking ocellaris clownfish. This includes wider black margins which divide the orange and white markings. Ocellaris clownfish usually have thin black dividing margins between the orange and white. This overall darker coloration of the percula is recognized by most hobbyists as the most recognizable difference between these two fish.