I have 6 20h's that I use for grow out but they are the middle step for me.
I use 5s to hold the fry for first couple weeks. If I have two batches of the same
type that are close in size I then put the 2 groups from the 5's into a 10 gallon for a month or 2.
I then take 2 batchs of the same fry from 2 10's and put them into a 20.
Finally they go to the 40 longs or 55's
Sounds confusing? LOL That way I have 3 or 4 different sizes of fry going at the same time for some of my peacocks. (not all. not enough room) So larger fry don't pick on the smaller fry so much.
I do not use the 20's for breeding. Like Matt said, too close.