Why do cats prefer fish to meat?

Cats have different nutritional needs than dogs. They caneat dog food and they will if they are hungry enough. Dog food generally has more filler (grain) than cat food and a steady diet will be unhealthy for a cat. Cats also may not find dog food to be palatable.

Additional Information

Dog food can seriously malnourish the cat after a period of time. Cats have far more nutritional needs than a dog and dog food doesn't contain these essential nutrients such as taurine. A small amount of dog food will not harm the cat, but this must NEVER consist as part of cat's daily diet.

Cats need a diet consisting of a high meat content - probably more so than dogs. Meat is mostly made out of Proteins and Fats, and cats use these as their primary energy source. Here are a few things that are present in cat food that are not in dog food:

Taurine: Cats cannot synthesize this compound (unlike dogs and most other mammals), so they must get it straight from meat. Animal tissues such as poultry and fish are natually high in taurine. Not enough taruine in the cat's diet can lead to heart problems and blindness.

Vitamin A is another component cats cannot produce. Dogs can use a compound called "beta carotene" (its what gives fruits and vegatables such as carrots the red-orange colour) and turn that into Vitamin A. Cats cannot. They need to get Vitamin A from meat.

There are also number of fatty acids cats cannot synthesize in their bodies but dogs can, so feeding a cat food specially made for them is the safest option as all the nutrients are included in the food.