No matter how you feed them, they are always hungry. Tilapia has short digestive track they eat a little bit at a time but most of the time.
These are in my CRAFTS set, and they are getting bigger. I use fish pellets to feed them.
Never over feed fish, especially in Aquaponics. Water will get murky and Ammonia will shoot up. If you see foam or bubbles in the fish tank just stop feeding them for at least one day and continue after water had cleared.
It's okay for them to go hungry, they will start to feed on the algae making water and tank cleaner.
Surplus greens is good, above is the Sambung Nyawa plants that I cut and throw it to give them something to bite.
Tilapia will eat greens, one of the best is Kangkung these they will nibble in no time at all. However before feeding them greens make sure they are really hungry.
There are loads of green from my Aquaponics growbeds and it's fish food.
After 1 day in the fish tanks, this is what left of the plants. Those stems can still be use as cuttings.