Maybe this is a side thought...
But you have a dog, fish and a bag of dog food. You won't feed it to the animal it's made for, but are asking about feeding it to the fish. Why?
Chances are you are doing the logical thing in regard to the dog. It's used to his normal diet. Changing it causes problems, as many animals are sensative to drastic diet changes that happen rapidly.
The same holds true with fish (generally speaking). It's not a good practice to suddenly switch up the diet - whether it's to dog food or just another brand of fish diet.
Thought I'd throw that in to think about since the ingredients and water quality concerns have already been discussed.