Aquaponic nutrients

Several people have asked me where the nutrients come from in the aquaponic systems.
First of all the fish breathe and excrete and that supplies a lot of nutrient.
As the system ages  soil accumulates in the bottom of the water troughs. This soil comes from rotted vegetable material and from the coconut fiber  that is in the net pots that hold the
vegetables.

After 6 months or so all kinds of creatures set up homes in the bottom residue . The most noticeable ones
are : a tiny gray shrimp with a long name and red worms like the ones you find in worm bins.
All of this activity provides a lot of nutrients.