In time, it should take to a variety of foods. Offer it mysis shrimp, chopped mussell, clam, pellets, plankton, things like Emerald Entree and Marine Cuisine, continue with the algae sheets. If the fish is reluctant to eat, place a small steamer clam in the tank partially cracked open. Brine and blood worms are okay on occassion.
I'd suggest soaking the foods in selcon or zoe for added nutrition.
How big is this fish?