My favorite tank had native fish in it. I grabbed the water and some mud from a local waterway, used that to jump start the tank and then added some fish from the waterway to it.
It was a pain getting some of them to eat fish food, but getting some copepods and mosquito larvae to feed them was never a problem.
If I ever get a chance to set my tank back up, I think I'll go that route again. There are some pretty fish in the USA.
