False percs are actually
Amphiprion ocellaris, and true percs are the real Amphiprion percula. Ocellaris can grow to a bit over 3", but percs usually do not pass 2.5". As said, true percs have wider black bands surrounding the white stripes. Generally, percs have 9-10 dorsal spines and 16 pectoral rays, while ocellaris have 11 dorsal spines and 17 pectoral rays, but this isn't 100% correct. I've also noticed that all ocellaris have a much taller dorsal fin than perculas.
Clownfishes by Joyce D. Wilkerson is a great book for any clownfish keeper, I highly recommend getting it.