my classroom aquarium has five goldfish - designated "feeder fish" - i bought them a couple of years ago and paid a quarter a piece i think. they have lived in the class since then and each summer i put them in a tupperware container on the back of my bike and take them home to their summer aquarium. then i pack them back up in the fall and they head back to the more spacious accomodations of room 212!! the hearts - algae of course!!