Aquaponics is definitely a thing. Lots of plants grow well, it's not really ideal for the fish, or for the plants though. Tomatoes and lettuce seem to work well enough when I've tried it (In my greenhouse in a small tank filled with water from my fishtank)
Because if you have low nitrates(Or nutrients in general) for the fish, it's too low for the best health of the plants. If you have high nitrates for the plants, it's too high for the best health of the fish. It's a tradeoff.Why isn't it ideal for fish? In our setup it will keep nitrates low.
Because if you have low nitrates(Or nutrients in general) for the fish, it's too low for the best health of the plants. If you have high nitrates for the plants, it's too high for the best health of the fish. It's a tradeoff.
Nitrates in my tank are pretty close to 0 with plants, so it's actually better than no plants. I would never add nitrates in tank for fish. Plants will get constant supply of nitrates, other nutrients can become bottleneck and can be maintained without affecting fish. There are test kit for phosphorus which might be only concerning plant nutrients beside nitrates. The key is to get right amount of plants.
Are you saying that the tank in the photo, with a large cichlid and a few other smaller ones and a small handful of pothos, has zero nitrates and that the plants have achieved this? Sorry, but I suspect that either your testing equipment or methods are faulty, or there is something else going on. That small amount of pothos could not begin to consume all the nitrate created by that much fish biomass.
If you are growing plants in zero-nitrate water, then by definition it is not ideal for the plants. They live in it and get what they can and need to survive, but they would flourish much more if the nitrates were higher.