Bloodworm, market shrimp, tilapia,NLS sinking pellets and floating pellets did expect to see it eat those thou.Sorry for your loss :/
This happened to one of my clown knives. He appeared perfectly healthy, but wouldnt eat. I tried virtually everything on the species menu. Eventually it starved.
What were you feeding it?
My polys love anything that is soaked in a bloodworm juice/garlic solution.