I'm in the process of setting up an aquaponics (recirculating aquaculture) system. The main fish being raised are Channel Catfish, and in a separate tank I am also attempting to raise Guppies as a primary food source for the catfish.
Catfish, being omnivorous and greedy, will eat almost anything. Right now, they're small (5"-7") and can't fit a guppy in their mouth. I am feeding them on commercial fish pellets but eventually would like to feed them the guppies, grubs such as soldier fly larvae, as well as a small amount of some vegetable matter like duckweed.
The guppies need their own food of course, and I'd like to know what type of food chain I can create that doesn't rely on purchasing or importing feed of any kind. Commercial feeds for fish are typically made from ocean-caught "trash fish" and thus are likely contaminated with mercury or other heavy metals, which is why I'd like to avoid buying feed pellets. It's also expensive.
Several things I've considered for guppy food:
- Mosquito larvae
Essentially, the only "free" inputs that are available are sunlight and oxygen (air). It seems like, in nature, that is enough to fuel the bottom of the food chain. So what is practical for a DIY system?