This is the standard stocking rate used by angel breeders for years;
Newly free swimming fry 40 fry per gallon
Two week old fry 20 fry per gallon
Month old fry 10 fry per gallon
Pea size bodies 3 fish per gallon
Dime size bodies 2 fish per gallon
Nickel size bodies 1 fish per gallon
Quarter size bodies 1 fish per 2 gallons
Silver Dollar size bodies 1 fish per 3 gallons
Potential breeders 1 fish per 5 gallons
Show Specimens 1 fish per 10 gallons
One breeding pair 20 gallon high tank
Stock beyond this at your own risk. You can stock smaller fish heavier if you do a lot of frequent large water changes. Stocking heavier with dollar body size or larger means having a spare tank of at least 20 gallons ready to go, as at this size pairing starts. Angels are cichlids, and will show the aggressiveness associated with cichlids when pairing.
