Pellets provide a lot of your cockatoo's nutrition, as they are balanced to give your bird what they need. Pellets can account for about 75% of your bird's diet each day. How much you feed your bird is based on how big your bird is. Read the back of the package to estimate how much you should feed your bird and talk to your veterinarian to confirm the amount. Your cockatoo will enjoy a wide range of fresh fruits and vegetables, so try a variety to see what it likes. Plus, a variety will help it get the wide range of nutrients it needs. Any grains you feed your cockatoo should be cooked and cooled.  For instance, you can try pineapple, blueberries, melons, and pomegranate, just to name a few. You can also use more common fruits like bananas, apples, and peaches. For vegetables, you can give your bird carrots, summer and winter squash, peas, cabbage, tomatoes, and cucumbers, among others. Your cockatoo can also eat cooked beans, like chickpeas, navy beans, and kidney beans, as well as cooked grains like barley, brown rice, pasta, and oats. Avoid anything with caffeine or chocolate, as well as potato skins, avocados, and peanuts with the shell still on. Limit how many foods you feed that are high in vitamin C, such as citrus, strawberries, kiwi, and broccoli, as too many of these foods combined with a pellet diet can lead to your cockatoo absorbing too much iron. Cockatoos shouldn't be on a seed-only diet, as it doesn't provide enough nutrients. They are too high in fat, and your bird will likely just pick out what it likes, leading to deficiencies. However, you can feed your cockatoo some seed as a treat. It shouldn't make up more than 5% of your bird's diet. You can also feed your bird nuts and table scraps as treats. For table scraps, stick to healthy fruits and veggies, mostly, though you can give your bird bites of other foods in moderation. Keep dairy products to a minimum. Cockatoos like to be around their flock when they're eating, and you're their flock! If your cockatoo is in the same room as your kitchen table, you can even feed it when you're eating. Take the dishes out of the cage and wash them with soap and warm water. Dish soap is fine for this purpose. Rinse them out thoroughly, then refill the water dish with fresh water for your bird.

Summary:
Provide parrot pellets for your bird. Make 20% of your bird's diet fresh produce, grains, and legumes. Include a small amount of seeds and other foods as treats. Feed your cockatoo when you're going to be around. Clean the dishes and change out the water each day.