Your Cockatiel has laid an egg and your wondering if the egg is fertile. Here is a simple way to check your eggs to see if they have a chance of hatching.
The best time to candle a cockatiel egg is around five days after your birds have begun sitting on the egg. Wait until your Cockatiel has left the nesting box and you have easy access to the egg. Do not try to run the birds out of the box. Startling the birds could cause them to trample the egg. Eggs that are shaken or rolled to vigorously can result in the death of the embryo.
Step2
Carefully hold the egg up to a bright light like a flashlight or lamp. If the egg is fertile you will see lines running from the yolk to the shell. These are the veins of the embryo. There should also be an empty space near the tip of the egg. This is the air sac that they baby will use days before it hatches. If you do not see these wait a few days and candle the egg again. If the egg is older and closer to hatch time you may not see anything but an air sac and darkness. This would be the baby bird taking up most of the room in the egg.
Step3
Do not leave the egg out away from the parents to long. You do not want the egg to become to cool or overheated. Gently place the egg back in the nesting box and wait for it to hatch.
Novice 
