I think that most fish would be destined for a slow death in a setup like this. In the OP it was mentioned that guppies had 3 generations, in a thriving tank that can happen in as little as 5-6 months.
One major concern would be nutrition, fish like guppies are not thriving when they are stuck eating (attempting to eat) elodea or algae.
What is the intended goal? There is no self sustaining system like this in nature, at least not on this small of a scale. If you had a larger tank with some sort of method to maintain a colony of shrimp or snails and a fish that could sustain itself off of them then maybe, but even then if it were a breeding group of fish then the food source would run out in as little as one generation.