This is not a "new way" to farm as its origins date back to ancient Egypt and Asia. This type of of agriculture has experienced an upswing as new technologies are applied to ancient techniques yielding magnificent results. My Common Goldfish we bought as feeders from my local petshop about 6 months ago and they have grown considerably. The size of the fish does directly correlate to the amount of waste it will produce, so if the goal is maximum yield larger fish would be in order, however this is merely a hobby system. Thanks so much for the question!