Marbled sleeper gobys will eat anything that can fit in there mouths. I currently have 4 different tanks of marbled gobys largest 16 inches smallest a little over 2 inches. First thing is tank setup the fish needs lots of caves wood and rock work to feel secure. If the have these things they will be much more active and feed better. I have never feed my gobys pellets and i never will. My gobys eat live fish,crayfish,crabs,earthworms,blackworms,river shrimp, fresh chopped tilapia,small mice and frozen worms and shrimp also to the smaller ones. If you never see your goby he most likley isnt happy with his tank. Also Marbled sleeper gobys are most active at night and early in the morning and this is when they should be feed. If you have a goby in a tank with cichlids throwing in pellets chances are hes getting scraps and in bad shape, it would be like feeding your cichlids in total darkness in a catfish tank and expecting them to eat. He also wont reach his full size and potential living the way he is. These fish can eat there own body weight in food a day so a few scrap pellets wont cut it. My large male will hand feed but only in the dark he hates the light.The only things they will really come out for in the light are live worms,live crabs or crayfish. Hope this helps