Because my cat's smell and taste ended up being affected by the cancer, he wasn't interested in the stuff she recommended, so I figured I'd make his last weeks as happy as possible and provided him with mostly store bought canned tuna. It was about the only thing he could smell that stimulated his appetite. Canned tuna in itself is not good for cats as a regular diet, as it causes certain problems with their skin I believe, but at this point in his life, it was quality and not quantity that I was looking for.
"She recommended a special diet which included feeding my cat fresh fish"
THAT DOES IT. LOL, Now I have an excuse to go fishing more often.
She was correct. Cats are carnivores (dog's too) and they do not digest grains the same as we humans... they turn to sugar in their systems.... they don't need diet foods, they need species appropriate food.
So sorry to hear about your cat. I love my big old neutered tom. He is the most loving cat I've ever had, and it will be hard when I lose him (he's about nine years old).