Fruits and vegetables

Apples, oranges, bananas, pears, peaches, green peppers, chilli, sweet peppers, canned corn, corn-cobs, cooked broccoli, raw spinach, raw dandelions, raw collard, kale, raw Swiss chard, carrot, carrot tops, and berries. Beta-carothene rich berries, broccoli and carrot is particularly good for colour-bred canaries (Red Factor and Yellow Factor canaries), to give them a rich, enhanced colour in their feather plumage, especially during the moult, when they are changing their feathers.

Small amounts of parsley.

Lettuce is only water and fibre, and contains no nutrients. But the birds like to eat them, so they can be used as a carrier-food for supplements and oil.

Do NOT feed: mango, tomato, avocado, apple seeds, mushrooms or chinese pea pods.

Some Dangerous Foods For Canaries

• Moldy, spoiled and poor grade foods.
• Avocado- the peel and seeds are very toxic to birds. I have seen mixed information about the fruit itself - I would not risk it.
• Coffee and coffee beans.
• Rhubarb leaves- whether raw or cooked, the level of oxalic acid in the leaves is poisonous.
• The green parts of tomato plants.
• Potato shoots.
• The green parts of potato plants.
• Cat or dog food- these can contain bacteria.
• Foods high in oxalic acid should be fed sparingly as oxalic acid can damage the kidneys and bind nutrients such as calcium, preventing proper absorption. These foods include vegetables such as spinach, beets and beet leaves, purslane, chard, parsley, chives, cassava and amaranth.
• Salty foods.
• Chocolate.
• Alcohol- this can be lethal even in very small doses.
• Yeast- uncooked. (Source)