Why

Peanuts are best avoided completely for a budgie because of aflatoxin, a poison produced by moulds that commonly grow on them. Aflatoxin is a potent liver toxin and a known carcinogen, and contamination cannot be seen, smelt or tasted, so a nut that looks perfectly fine may still be harmful. For a bird as small and vulnerable as a budgie, whose liver has little reserve, even a low level of this toxin is a serious risk. Given how hard the danger is to detect, this site advises never feeding peanuts.

What to do

Keep peanuts and peanut-containing foods, including many cheap seed mixes and peanut butter, out of your budgie's reach, and check labels on treats. If your bird has eaten peanut, especially any that looked mouldy, discoloured or old, contact an avian vet for advice rather than waiting to see whether the bird becomes unwell.

How much & how often

There is no reliably safe amount of peanut for a budgie, because harmful aflatoxin cannot be detected by sight or smell. Avoid them completely.