Have you tried pre-soaking pellets in the juice from frozen blood worms? I have trained numerous non pellet eating fish in this manner, including young fish from SE Asia that were raised exclusively on blood worms. It takes some patience, and time, but has worked every time.
Presoak your pellets of choice in the juice of frozen bloodworms. Only feed in AM when the fish is most hungry, and do not offer any other food. After a week or so of this your fish will slowly but surely start nibbling on the food. Once it is eating like gangbusters slowly wean off of the presoaked food, over several days, and convert to 100% pellet. If your fish likes the taste/smell of krill, use a krill based pellet, and you could also presoak the pellets with freeze dried krill mixed in with the blood worm juice.