I want to be prepared with a quarantine tank and not wait until I'm ready to get some new fish. We have a 20g tank with 2 Platy and 3 Swordtail right now. Eventually, I'd like to add either a few GloFish (Danio or Tetra) or a few bottomfeeder species. So I don't need a big quarantine tank for either of those. I have an old, small Betta tank (maybe a couple gallons). Would that be big enough for a fairly simple quarantine tank? Otherwise, I will probably go the plastic container route.