Are you after an all male tank?
In my six foot, I have about 15 fish total, but do not like to be overstocked. You could fit a lot more in, about 30 depending on species and filtration.
Go for male fish that don't look similar and if you want to have females remember that cross breeding is rife with peacocks as females look similar.
I would go for a mix of haps and peacocks. See what is available in your area and make a list. From there we can advise a little better [emoji106]