If you want, try blood worms, I never really liked them b/c I seem to loose more to the filter before they can eat it all. I feed mine market fillet and earthworms, but if yours likes bloodworms, go for it. I would first try to feed whatever it is that you normally would, just try with lights low and as little stress as possible. In the wild juvenile juruense face upstream and eat whatever hits them in the mouth. Trying putting the food right on its lips, works for mine everytime. Might be a reflex, but IDK.