First off, let me say that I do know that we are not talking about Aquaponics here....OK? Now then, with that in mind and, yes I can see where this system could suite someone with very limited space, however:-

Worm tea is well known as about the best fertilizer there is. They can produce a lot more of their fertilizer than fish grown in the same space. A worm bin can go through 10 pounds of food a week. That is a lot more than you'd feed fish, so you'll get a lot more nutrients. This is basically just hydroponics with worms as the nutrient source.
That little statement in RED is where I have to back up...you might be able to use the tea from the worms to grow veggies, sell the worms, sell the worm dirt and the worm tea, but you can't eat any of these items and that’s where the fish come into play.

The whole object of being self-sustaining is to produce as much of your own food as possible without going to the store to pay an outrageous price for possibly contaminated and definitely chemical filled meats etc from the store….FISH..or did I miss something..?