It's never ending, I know… have you tried other proteins w/him before? Beef and pork seem to work well w/my bullies… I use Fromm's Four Star for Walter and Fromm's Puppy Gold for Willow. I was just curious why you choose the Fish… I have given Wally Lamb and Fish before and I just felt like he was starting to have issues. You can give him pure pumpkin to firm up the stools, sometimes loose stools mean they are getting too much dog food but your amounts sound correct.
Oh I meant to add that a month seems a reasonable amount of time, he should be adjusted by now.