normal rule of thumb after the tank has been up for 6 months is 1 inch of fish per 2 gallons. ABSOLUTELY NO MORE. Unless you were going for the concentration camp look.
IMO a 10 is barely large enough for one Ocellaris (false Perc). Can you go with a true Percula? I believe a pair of true Percs will work in a 10 gallon if you are diligent with water quality.