I have a tropheus I bought from petsmart that would only eat bug bite pellets and random debris/algae he finds in the aquarium but will ignore the crushed peas I throw in the water. What am I doing wrong?
That's normal. They are not vegetarian. They are limnivore or so called Aufwuchs grasers. Means they feed on algae and all the small creatures living in the algae.
I feed mine high quality flakes with minimum 10% spirulina (good substitute for algae) as staple food and in addition some pellets and some low fat low protein frozen foods like daphnia.
Tropheus are also a social species. When kept alone they get depressed and refuse to eat their veggies
Seriously though, a lot of folks keep individual tropheus but they definitely do best in social groups.
Also, like any fish species, a sudden change of food type is often met with what you’re experiencing. Especially with such a big change in size & texture. Your dub probably doesn’t even recognize a pea as food.
I have duboisi Maswa, moorii lufubu & black caramba red bishop groups. Like
Milingu I feed a high quality spiraling flake & omega one veggie pellets