>>943154yeah. fish food. a tank that size, you can buy small pond pellets.
you could try having them feed off of insects as they would naturally, but I'm not sure that will be sustaining. and since you're genuinely asking questions, I'll list a couple more tips that come to mind.
The tank the fish are in can't be completely full, the water wont cycle properly if it can't move(splash) significantly from the water flowing in.
hydroponics is a theoretically sound process, but it requires a lot of fooling around with the water flow. too much and the plants don't get enough nutrients, too little and they sap the water of it's resources and generates mold. and for obvious reasons, it has to be reset every spring because of winterizing the system(assuming it's outside).
the ph requirements of the plant are very important with hydroponics. it's not impossible to raise watever you want, but until you have a significant amount of decaying plant matter, the water may promote mold. to fix this you can introduce some moss(sphagnum) too the "top tank". sphagnum has a ph of about 4 and is great for preventing mold in most systems without introducing too much acid. the moss doesn't have to be alive, just natural and in a non processed state(whole with roots).
and if you use clay balls instead of gravel in your grow bed(or a mix) you'll get better results. water travels across the surface of clay balls which makes filling the grow bed unnecessary. this is specially useful for plants that are sensitive to having a saturated stalk for extended periods of time.
any other questions, I'll be happy to answer if I can. if you want to do your own research you should look into planted fish tanks and large planted tanks with a "sump" setup. don't get discouraged, once you've got a rhythm with these things you tend to just go into autopilot when there's a problem and solve it pretty quick.
