If your fish is tank raised I would do the following. (wild caught im not sure if this would work, although i have heard its the same process)I have some smaller shyer fronts in with my larger fronts and larger haps. The little ones would get a tiny amount of food compared to the haps and some of the more dominant fronts, so i put my pellets into a "shaker" style can and put in food all along the front of the tank, that way even the shyer ones have a chance to snap some up if they want to. I noticed more food goes in that way, mine clean it up good, but you might need to do more clean up until they and you get used to it. If he still wont eat anything but frozen foods then i would not give him any frozen food at all and he will get so hungry he eventually will eat the sinking pellets. By feeling bad for him and giving him some frozen food here and there your just prolonging the process so i would stop frozen foods totally. It could take a long time before he eats more than just what it takes to just stay alive, he might take several weeks till he appears to like it...