She's lovely Ben but Barb is right, 3 meals a day is not enough for such a young puppy. She really should be on at least 4 meals a day - our pups would have breakfast, lunch, tea & supper at 6 weeks old. We feed a good quality complete puppy food (Nutro) 4 times a day but if you are going for a mixed diet, there is nothing wrong with fish but serve it with some rice or with the puppy mixer you can buy (Pedigree Small Bite Mixer) to make a more balanced meal. You could also feed scrambled egg sometimes as one of her meals as most pups love this & its excellent food for growing pups.