+1 with
J
jaws7777
, maybe the O is the problem, polys dont fight back when getting bullied by other fish.
On the other hand your lap looks like a cb, some polys get stunned and just slow down on growing especially if the fish is not a big eater, giving the poly some feeders moght be a bad decision since to can introduce some parasite to the fish. I would try to starve the poly to about two days and give it some food, i would try to feed it silversides since the smell is stronger than tilapia, i will also feed it at night so the O wont take most of the food.
On the other hand your lap looks like a cb, some polys get stunned and just slow down on growing especially if the fish is not a big eater, giving the poly some feeders moght be a bad decision since to can introduce some parasite to the fish. I would try to starve the poly to about two days and give it some food, i would try to feed it silversides since the smell is stronger than tilapia, i will also feed it at night so the O wont take most of the food.