You can only grow so big in so little of media. Time to transplant into larger containers.

That's aquaponics if you have fish in it. You're not going to grow anything that fruits or flowers in that. Fish waste is almost entirely nitrogen. You can add chemical or organic fertilizers, but I would guess that 's not good for the fish. You can try removing the fish to an aquarium and using a hydroponic fertlizer.

If you just want to put pots of plants on top of the aquarium for aesthetics, double pot them so the inner pot has drainage and water with plant nutrients in the outer pot, letting the inner pot act as a regular plant pot and the outer pot as a barrier to contact with the fishwater.

If you want to grow real above water plants in the aquarium water, try Kangkong (Ipomoea aquatica) or Watercress (Nasturtium spp.) For these suggestions the roots only can be submerged in fresh water and the stems and leaves are allowed above in air and light, and if you are careful you can grow them nicely.

If you want a challenge to see if you can get a flower floating on a light collecting leaf, try the Star Lotus (Nymphaea nouchali). It is exceptional in that it can flower floating on the aquarium surface if you keep it trimmed and add a tolerable trace amount of iron chelate to the water.

This post was edited by PupillaCharites on Wed, Sep 18, 13 at 3:38