The fish.. um... deposits? are supposed to have a certain amount of DR. I forget if its 3 or 5...
But, I noticed that some dont have the DR while the majority do. One that I specifically noticed that doesnt have it is Trout. (and maybe pike)
Edit: oh yeah, and the hunger thing... Fish seem to be filling you up about as much as a raspberry currently. Likely has to do with the fish specific fillets. I had trout and pike, they currently have 1 charge and are less filling than they were previous to the last update.