I know it doesn’t sound realistic but my 8 inch occel didn’t eat for over 6 months. Wouldn’t even go after live food and only saw him nip at 1 or 2 guppies when I had him in my hospital tank. He looked very healthy the whole time except for getting the concave stomach after about 4 or 5 months. Always swam around with tank mates and showed no signs of disease. I performed everything in the book and finally decided there was nothing else I could do and let him live his life out. Out of the blue, took a small piece of shrimp while feeding my others and has made a complete turnaround. He is now a great looking 14 inch occel (one in avatar). He would eat 20 shrimp a day if I would let him. Might sound unbelievable but I controlled all the food in that tank and watched him every feeding to see if there would ever be improvement. It shows you how amazing fish truly are.