posted 9 years ago
Fish don't really need to be fed that often to be kept alive. They can usually go for at least a week without being fed. A system running solely on flies will probably keep plants and fish alive, but perhaps not much more than that. If you're alright with maybe only growing greens (they have low nutrient requirements, unlike fruiting plants) and having slow fish growth rates, then by all means.
Even fish food doesn't quite contain everything plants need. Aquaponic systems usually need a supplemental source of calcium, potassium, and iron in addition to regular feeding.
"There is nothing, Sir, too little for so little a creature as man. It is by studying little things that we attain the great art of having as little misery and as much happiness as possible." - Samuel Johnson