the reason i think your not having any luck is because yarelli have very poor vision, i think they depend on the movement from live prey. all the food you have tried doesnt move. try live night crawlers. I got mine from aquascape too, and they told me they were giving him goldfish. but i try not to feed live feeder fish so the first thing i offered him was night crawlers. I give him 3 feeders about once every month just cuz i like to see him hunt. mine will pound anything. he is like a freakin oscar. as soon as you open the top he races up thinking he is about to get fed. he even chases fingers. i had the same issue with my black devil cat and my tigrinus but i starved them and they started to take the night crawlers. in the future if you want your fish to eat a certain food offer them that first. a fish like the yarelli are always anxious to eat you'll get it in time. patience my friend, starve for a week. i starved my tig for 2. the longest its ever taken me to wean a fish on to a new food was 3 months of constant starving.