While you shouldn't feed your cat scraps or special "snacks," these foods don't necessarily provide a complete and balanced diet. Even if you do feed them these foods, it should be in moderation. Never let your cat develop a strong preference for any one food, as it could harm them. For example: 
Liver: Some cats love to eat liver and will stop eating the rest of their food. Liver contains a large amount of vitamin A, and excessive intake of vitamin A can lead to muscle stiffness, neck pain, bone and joint deformities, and liver disease.
High-fat foods: If a cat's diet contains a large amount of high-fat fish or fatty meat, it will lead to a deficiency of vitamin E, which can cause inflammation of the fat deposits and extreme pain.
Raw fish: Some raw fish contain an enzyme that can damage vitamin B1, and a deficiency in vitamin B1 can lead to neurological disorders, which can be fatal. This enzyme can be destroyed by heating, so fish must be cooked before feeding it to cats.
Meat: While a cat's diet should primarily consist of meat, it's not advisable to feed it only fresh meat. This can lead to an imbalance in the intake of minerals and vitamins, thereby triggering severe bone metabolism disorders.
Dog food: You shouldn't feed your cat dog food either, as the nutrients in dog food are insufficient to meet a cat's needs. Cats are carnivores, while dogs are omnivores, and therefore, dogs don't have the same nutritional requirements as cats.
Cod liver oil: Caution should be exercised when supplementing cats with special vitamins and minerals, as improper use can be harmful. Excessive consumption of cod liver oil can lead to excessive intake of vitamins A and D, thereby triggering bone diseases.
