Would for me,,entirely depend on what type of water I had readily available from the tap, and which I would be using for weekly water change.
If My water was soft,,then I would be looking at small fish considering the tank's size,that enjoy soft acidic water.
If my water was hard'alkaline,,I would be looking for small fish that enjoyed that type of water.
Would not consider anything that had potential of exceeding three inches as Adult fish.
The most important medication in your fish medicine cabinet is.. Clean water.