Base diet:
Your cockatiel’s diet is extremely important and is the key to having a healthy cockatiel along with exercise. Unfortunately many caged cockatiels do suffer from obesity so special attention to diet and
exercise is required. Give your bird a good-quality cockatiel seed mix (not parrot mix). These are readily available at pet stores and supermarkets. Be aware though that most ready-mixed cockatiel seed contains far too many sunflower seeds and these are extremely fattening. For this reason I
tend to make up my own mix for my cockatiels. I buy a 50/50 mix of budgie seed and plain canary seed and then add a few sunflower seeds. Do not buy the seed in bulk - you are best to purchase small fresh amounts. Alternatively, you can offer your cockatiel a pelleted diet. Your cockatiel’s diet must be supplemented with fresh fruit and vegetables on a daily basis. Fresh drinking water is required daily. Also make available cuttlebone, and calcium, iodine and mineral blocks.
 

Pelleted diet:
Many avian vets recommend a pelleted (or formulated) diet for pet birds rather than a seed diet. Seed diets must be supplemented with fresh fruit and vegetables, vitamins, calcium and other minerals. Pellets however are supposed to include all of a bird’s nutritional needs and are often referred to as the complete and balanced diet. Generally they consist of a mixture of ground up grain, corn, vegetables, proteins, vitamins and minerals. There are many brands of pellets now available. Some are colored and come in different shapes and sizes, although the more basic pellets are one shape and size and a brown color. You should be able to purchase cockatiel pellets from your local pet store or avian vet. Be sure to follow the packet directions carefully, taking special note of the quantities and storage requirements. Also, ask about providing supplements to your cockatiel once it’s on a pelleted diet. Because pellets are a complete diet it is normally detrimental to offer extra supplements, so be clear about this. Pellets are fairly easy to introduce to a young cockatiel during the weaning phase, but trying to convert an older cockatiel from a seed diet to a pelleted diet can be extremely difficult and may require the assistance of an avian vet.
 

Fruit and vegetables
An all-seed diet often results in an unhealthy or overweight cockatiel, so your cockatiel’s diet must be supplemented with fresh fruit and vegetables on a daily basis. You can try the following:

Fruit: apple, grape, guava, kiwi fruit, melon, nectarine, orange, peach, pear, pomegranate, plum, strawberry, tangerine, watermelon.
Vegetables: bok choy, broccoli, carrot (chopped or grated), celery, chard, corn, lettuce (not
very nutritious so don’t offer this regularly), peas, silverbeet, spinach, sweetcorn, watercress,
zucchini.

Favorites with cockatiels tend to be apple, peas, silverbeet, spinach and sweetcorn. Note that the fruit and vegetables should be provided: thoroughly washed, in small pieces, at room temperature, unpeeled, free of cores, stones, pits or pips (note, the leaves, pits, pips and stones of apples, apricots, cherries, peaches, pears and plums can be poisonous), ripe (be careful not to give unripe food or food past its best), fresh (obviously this will be the most nutritious for your cockatiel but you can use frozen or canned occasionally) Attach the fruit and vegetables to the cage with a clothes peg, plastic food clip or spike bought from your pet store. Remove any uneaten offerings at the end of each day. Be aware that your cockatiel’s droppings may be runnier than usual with an intake of fruit and vegetables. Some cockatiels will not take to fruit and vegetables straight away. Persevere as it can take up to a year before your cockatiel will eat them. Fruit and vegetables are an essential part of your cockatiel’s diet so offer them washed and fresh each day even if these go untouched - do not give up!
 

Vitamins
Vitamin supplements in the drinking water once a week or fortnight are a good idea, although do not leave these in the water for long as bugs can grow very quickly. For this reason, I actually prefer to sprinkle powdered vitamins onto the seed or moist food, eg apple pieces or spinach. Either way, be sure to follow the product’s directions with regard to dosage amount and frequency.
 

Treats
Small amounts of 'people' food are fine for cockatiels occasionally. They can have a nibble on crackers, cereal such as cornflakes, hard-boiled egg and wholemeal bread. Also try rice, pasta, potato, pumpkin and sweet potato - these must be offered cooked, not raw. Cockatiels enjoy spray millet and seed treats such as honey bells or sticks. However, these are fattening and should be offered as occasional treats only. Pet cockatiels can become overweight very easily so I recommend offering spray millet once a week if your cockatiel is fairly active, or if not, only once a fortnight. Seed treats are best given at two monthly intervals.
 

Salt
Pet birds do tend to crave salt. This is probably due to them lacking some form of mineral or
vitamin in their diet. A pinch of salt occasionally is okay, but too much is dangerous and can be detrimental to your cockatiel’s health.
 

Milk and other products
Birds are lactose intolerant. This means they are unable to process the lactose (milk sugar) found in dairy products as they lack the enzyme required to break it down. For this reason milk should not be given to your cockatiel as it will result in an upset digestive system and severe diarrea. Caution must be applied with feeding any other dairy products as they all contain a certain amount of lactose. An occasional offering of low fat yoghurt, low fat or mild cheese or low fat cottage cheese is acceptable. I must stress though, occasionally and tiny offerings. If you notice your cockatiel has diarrhea after eating any of the aforementioned cut back immediately.
 

Do not feed:
Never give your cockatiel alcohol, avocado or chocolate - these can kill your bird. Also avoid
asparagus, aubergine or eggplant, mango, cabbage, caffeine (tea and coffee), junk food, milk and cream, raw potato, and rhubarb (including the leaves). Use your common sense when it comes to feeding your cockatiel. Many plants and food items are unsafe, so if you have any doubt, do not offer it to your cockatiel.
 

Grit
There is a lot of debate on the subject of whether or not cockatiels require grit or gravel to help with the digestion of their food. My opinion is "no", they do not need grit or gravel as part of their diet. I have spoken to many bird experts about this and their opinion is the same. My cockatiels and budgies have never had access to grit or gravel, with no adverse effects. Cockatiels in the wild seek out bits of grit to aid in the digestion of their varied diets, however pet cockatiels have a fairly standard diet of seed or pellets, and fruit and vegetables. They hull or crack the seed with their beaks or simply grind away at the pellets so can easily digest these diets. Cockatiels provided with grit can gorge themselves on this, especially out of boredom or when they are ill, with damaging results to the crop and digestive system.