cucumber, earth worms, fresh lettuces, almost any of your leafy greens, do not use iceberg lettuce as it's almost void of any type of nutrients... i like to chop it up really fine and put it in the tank the parrots will love it and because most of the blood parrots i have ever seen can't seem to move their lips very well in order to tare off bits and pieces it's a great way to make sure they get some. my cichlids loved romaine hearts cut up into little strips.
hope this helps,
Brandon