I think it is ok to breed, raise, and grow out in 20 gal tank. I do not see why not.
When they are very small: I fortunate have a feeding bags (human medical supplies) that can adjust the volume flow so I hand the bag up and let it drips slowly, 1000ml drips about 15 minutes.
But I also you can use small cup and pour it into the tank slowly on the side of the glass. Or you can hang the plastic cup inside the tank and pour the water into the cup, when the cup full it will overflow into the tank. Just do it slowly. It will overflow w/o much bothering the fries.
Just control the way you pour the water into it that has less disruption.
Just your creative thinking.
For example you can use a small plastic basket or funnel and place a coffee filter and pour the water into it it. It will slow down the water and less disruption.
Make sure you mix water conditioner first before you pour it in.
Last edited by tanseattle; 11-10-2012 at 04:59 PM.