Sometimes delivering a varied diet to your fish can be difficult. Finicky fish are hard to feed and many individuals may actively take only one type or brand of food. This single food diet presents many difficulties, as the fish is obviously not getting all of the vitamins and nutrients it needs in order to stay healthy long term. To provide that varied diet, you may have to get crafty and try to trick the fish into eating something it normally turns its nose up at. If the fish is a tang that will only take frozen algae-based foods, then try feeding other types of foods in the same fashion. It would even be helpful to mix the food and hope that the fish mistakes the new food item for what it is already accustomed to. The fish will realize that the new food items is both tasty and nutritious, effectively expanding the diet of the individual.