When you are feeding, try soaking food in crushed garlic and selcon (vitamin supplement). Try all different kinds of foods and algaes. The garlic makes fish crazy. It looks like a feeding frenzy in my tank when I put any kind of garlic extract in with the food.
I prefer to crush my garlic fresh, it is said to be the "best" way for them to get the goodies they need from the garlic, but I have also used garlic extreme, but it is expensive and I always question how long does it really last and how long has it been at the store. If you soak brine shrimp in the selcon, even they can become an ok food source, and most fish love brine shrimp, use in moderation as a treat.