ok, the math, as i said, you need to figure the adult size
so:
2 percs=6 inches
yellow tang is 8
dwarf lion 7
angel minimum 7 inches(most species are 12+), but here are the dwarf angels, 3 to 4 inches
butterfyly 6 minimum(most are larger)
now by my account that is 34 inches of fish in a 55 gallon(minimum, depending on hte species)
tangs, as i mentioned should have more seimming room, and for hte other general stocking
the general rule for sw is 1 inch per 5 gallons, now, this can often be pushed a bit, but i woudl not hink that much, that is over 3 inches per 5 gallons, wiht a real good biofilter and a stable system, i would not exceed 1 inch per 2 galons, but as i said, that is only a general rule, but fairly reliable
adn as i said, you should not consider a 3 inch dwarf lion as 3 inches, it is a 7 inch fish, it will grow, and some believe that they willll grow only to the size of the tank, THIS IS NOT TRUE in sw
HTH