Uhmm
So I am assuming that you dont mind the plant and fish in the same water close loop system.
But you do mind the complicated many buckets/growing medium setup.
Ok so instead of having a seperate elevated Nitrofixing/plant component, we could incorporate it into the water.
We could make a shallow rock/growing medium edge portion of the fish/water area.
Now what plants could we have in there, submerged or with wet feets.
Ceratopteris thalictroides, Hygrophila polysperma, Rotala spp, Glossostigma and Lilaeopsis, Nymphaea (water lily/lotus),
Lemna minor (duckweed), Azolla, Salvinia, Aponogeton.
Fish that will eat algae, tilapia (warm water only 70F)
Bottom of the food chain fish that will eat any type of plants.
Silver dollars, Loaches, headstanders.
You dont want the complicated aquaponics system with elevated grow beds.
You dont want to grow the food pellets/zucchini on land and then bring it over to the fish.
You dont want to have a "dirty" looking fish pond
So are you OK with a natural looking pond with the algae and huge aquatic plants(duckweed) that some might call dirty/nasty.
Fish waste>nitro fixing bacteria>Nitro for plants>Plants> Fish
Are you thinking of a system where the "PLANTS"/tomatoes we are growing are for humans consumption or where we just give the fish all of the plant to eat.