This Anemone Fish can be recognised by its orange colour with three white bars and black markings on the fins. It grows to about eight centimeters (three inches) in length. 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.
I hope this helps.got it from website so not my own words. I dont know that much.
Here is some more on the 2 species with a photo of each.
Percula Clownfish(True Percula)
Because of its name,
Amphiprion percula, it is the
True Percula Clownfish.
Typically orange in color with three white bars, with the middle bar having a forward-projecting bulge.
Has
10 (rarely 9) dorsal spines.
Usually has jet black margins of varied widths around its white bars, often of which can be rather
thick.
Distribution of this species in nature: Northern Queensland and Melanesia (New Guinea, New Britain, New Ireland, Solomon Islands, and Vanuatu).
False Percula Clownfish(Ocellaris)
Typically orange in color with three white bars, with the middle bar having a forward-projecting bulge.
Has
11 (rarely 10) dorsal spines.
The spinous (anterior) part of the dorsal fin is
taller.
May have no black margins present, but most often has thin, never thick black margins around its white bars.
Distribution of this species in nature: Andaman and Nicobar Islands (Andaman Sea), Indo-Malayan Archipelago, Philippines, northwestern Australia; coast of Southeast Asia northwards to the Ryukyu Islands.