How to stop biting parakeet?
I had my hand raised parakeet for almost a year since I was a baby. The first six months were great, it was Playful and affectionate, like being treated like it was a great pet. In recent months it has gotten increasingly more aggressive to the point that only I can handle if he is on the floor and wants to be picked ... is released even if you feed or change their water. Any attempt on my part to make that stop me bleeding. Nothing in his environment has changed, except that this seemed to start after I went on a business trip and went downhill from there. Regular travel is part of my situation and I'm at the point where you do not want to have, if this continues ... any suggestions would be greatly appreciated!
Parrotlets reach sexual maturity 6 months and 1 year of age. This is probably the reason for his change in behavior. Men are worse than women for being so brave and aggressive in defending their "turf." It is likely that business trip was precipitated worsening behavior. Being away and change your schedule may be annoying to any birds, and parrots are no exception. I have a very brave man (taking care of 4 now) who was always attacking my hands when changing food and water dish. I calmed down a bit, introducing the hand and stand a reasonable distance. I had to get to attack, but after the first stab and nothing happened, their attacks became very mean and then stopped and stepped up! 
Every day it starts again, but over time their "attacks" are less bold and give up that much fast. You do have to be patient, especially with these children. They really believe they are BIG Amazonas (their larger cousins) are very bold and most of time. But if you call his bluff, they are not sure what to do next. (A bit like a dog chasing cars .... "Rover hey, what you gonna do if you catch him? "LOL) Do not take your parrot's behavior personally, it's just a natural response to their" territory "invaded, and he will calm down if you respond calmly confident. 
Littletweet.com : Paige with "Marlee" the Turquoise Parrotlet Doing Tricks!