Cockatiels are friendly peaceful birds, but they can be known to argue among one another over good nesting spots and sometimes over food.
Cockatiels can mix well with birds from different species such as canaries, finches, budgerigars and other small parrots like parakeets. They should be separated from larger birds from the same family who may attack them.
You can keep a cockatiel along with a dog if the dog is friendly and will not attack it. You should keep your cockatiel caged and away from any cats as they could approach the cage and try to get in, while frightening your bird.
Fish tanks need to be covered up if you let your cockatiel out to fly in the same room. Ensure that no poisonous plants are in the same room as your cockatiel when you let them out to fly, this could cause stomach problems and even death if they were to eat poisonous plants.