Hi There Brian,
If you were to have livebearers eg guppies, you would probably find that in a smallish tank that none if any would survive, and those that would survive you can give away or sell. Yoyu can find some interesting ones around, just a matter of h8unting for them really
What you will need to considor aswell is any decoration you are going to have I.e driftwood, rocks etc and how big they are goig to be.
also I would forgo the silver dollars as from my understanding they get quite large, not sure how fast they grow, but why buy something if you know that further down the track you are going to have to rehome them any way.
just my thoughts on it where I can comment.
B