Being nocturnal predators, it may be difficult or impossible to feed your specimen during daytime hours. My advice is to introduce live foods either at dusk/dawn (actinics on only), or lights out. Live foods can include the commonly available brine shrimp (artemia), or mysis shrimp. If mysis shrimps are not available, you can substitute freshwater glass/ghost shrimps. Be sure to feed sparingly at first until he's taken to his new diet. Afterwards, slowly wean it unto frozen and (if you're lucky) dry foods. If your tank's zooplankton population (copepods, amphipods, etc.) are heathly, supplemental feeding may be unncessary; just let it hunt.