Mynah birds can only thrive on a proper diet, one that is low in iron. Unlike most other birds kept as pets, they are not seed eaters. The bulk of a pet mynah's diet should come from manufactured pellets made specifically for mynahs and other soft-billed birds, with other elements added for variety.
Mynah birds often suffer from a blood disorder called hemochromatosis, which causes them to absorb and store too much iron in their bodies. This causes the bird to have an enlarged liver, and damages the liver's function as well. As the disorder progresses, the liver problems place a great strain on the bird's heart. Therefore, those who wish to keep mynahs successfully as pets must take care not to allow too much iron in their diets.
Though mynah birds live on fruit and insects in their natural habitat, the easiest way to see that they get the proper nutrition is to provide them with commercially available pellets. The package should specify that the pellets are for mynahs (or other soft-billed species such as toucans), and it should state that the food is low in iron. In her article, "Feeding Your Pet Mynah," Kathy Butterfield recommends that it should have no more than 150 parts per milligram. Though mynah pellets can be hard to find in your local pet store, they can be ordered online from several sources.
Mynahs love fruit, and will be happier if you give it to them. Chopped pieces of apples and pears are safe for them to eat; bananas are very high in sugar content and should be used sparingly. The acid in citrus fruit makes it even easier for mynah birds to store excess iron in their bodies, so don't give your pet oranges or lemons. Any fruit you do give them should be ripe, and you should remove the seeds--some seeds can be poisonous to mynahs. Raisins have relatively high levels of iron, so mynahs shouldn't eat them.
Though mynahs can eat some vegetables, you should always check the iron content of any vegetable you want to feed them. Broccoli is too high in iron, as are peas and sweet potatoes. Turnips and radishes are low in iron, but tend to be denser and harder in texture than what mynah birds usually eat. Don't be surprised if your pet rejects them in favour of fruit. If you feed your bird turnips, be sure to cut them into small pieces.
Because mynahs eat insects in the wild, some pellet formulas include an insect-based component. Some mynah bird owners feed their pets mealworms. Butterfield asserts that this is not necessary for mynahs in captivity, and goes on to cite a risk for iron build-up. The "Pet Care Tips" website, however, notes that "Mynah pairs need mealworms during the breeding season and when they are feeding their babies." If you only have one mynah, or don't plan to breed them, you can skip the mealworms without guilt.