The system I am building is not ready for fish yet.
I have been reading about commercial fish foods, specially those for Tilapia.

When I was a kid, we used to go fishing and put a little dough ball on our fishing hook and catch fish. We caught almost everything with it. So, I was thinking Tilapia being mostly vegetarian, if I mix some other stuff with dough it might work and at least I know there is no chemicals and preservatives in it.