Apisto not eating

[graucow]

Hello, I have a male apisto in my 20 gallon tank and to my knowledge it has not eaten since I got it (around 3 weeks ago) it seems as if it puts food in its mouth chews it then spits it out. I've tried flakes, pellets, and frozen blood worms. I would rather not have to feed it live food all the time. It looks healthy to me but i still have not seen it eat. Does anyone have any advice on how to get it to eat?

Tank params were good when i last checked. Here is a picture of the fish taken recently.