Marshall's food is not that great and much more expensive than necessary. I use Purina One kitten food. The major things looking for food are the fat protein, fiber, and ingredients. You want the first two to three ingredients listed to be meat. Rice, wheat, corn are no-nos for ferrets. Many people also try to stay away from fish, because that increases their smell. I lost a ferret to adrenal gland disease. I adopted these two ferrets from a guy who did not take care of them. They came to me over six years old and one had a bad case of adrenal gland disease, past the opportunity to operate. The other is still around and is the hardest biter I've ever seen from a ferret. I always recommend adoption, but make sure you are comfortable with the ferret. I thought of these two as my charity work, because very few people would have helped them.Even though she bites, I love her just the same. Nip adrenal disease early is the only hope, good job for looking out and going to the vet. I go to a guy who has 20 years experience with ferrets and his studies were focussed on ferrets. In fact, on his building has the shadow ofa dog and a cat like a regular vet has, but then a furry little ferret next to them. It's Shaffer Animal Hospital and he is great care for ferrets. If you're happy with your vet, stick with him/her. I've seen a list of best foods, by ingredient list and prot,fat,fib content. Actually, the best food is some type of dog food you can only get at local pet stores, not chains like Petsmart or Petland. Petland did just start carrying this new type of food that had great quantities and list of ingredients, I forget the name, but it was at the one in Waterford. It is a cat food. Most ferret specific food are crummy cat foods with a different label to charge 3X's the price. Their diet consists only of certain products, many of which are low in content or not included in the ferret foods out. You really want chicken, lamb, meat or meal. No soy, corn, etc listed above in the top 2 ingredients. No fiber over 3%. High fat and protein(I forget the exact minimum proprotions, but can get them if you can't find them out).