In fact, fish is not even a natural part of a cat's diet. Vitamins Vitamins are used in the energy-producing reactions of the body. They are important in wound healing, tissue repair, maintaining healthy skin, haircoat and bones, and in blood clotting. Many animals, including dogs and people, can synthesis some vitamins, such as vitamin A and niacin. This is not true for cats.
Cats require both vitamin A and niacin in their diet.
These vitamins are found in animal tissues and again, their requirement makes the cat a truly carnivous animal. Because cats have different requirements for the levels of vitamins in their diets, they should not be fed dog food or vegetarian diets . Vitamin deficiencies are rarely a problem in healthy cats eating a wholesome diet. Deficiencies occur if a cat is fed a poorly formulated diet or food that is improperly stored or preserved. Vitamins are subject to rapid degradation in high temperatures during the cooking process.