Not sure about the logistics of oxygen and temps, etc. But what about gold fish? You could grow out common gold fish that they sell as feeder fish...
google D. rerio. They have been heavily studied for their regenerative properties. Their dorsal fin can be completly removed and it will still grow back.
There is a difference in being "fed" and what the fish does by nature. You can fed an Oscar once or so a week, but if you drop in 30 feeders,
Sol, I recently had the tail grow back on one of my silver hatchets in my 10g shrimp tank. No idea who/how it happened, but one day I noticed it wiggling
I agree with Freshy. You should just go with a 10 gallon. it will be more fun to work with (aquascaping, cleaning, filter and light selection) you have