That's a MACAW Parrot. To be more specific it's a military Macaw. The Macaw is a large parrot and can come in a variety of colors, there's a Blue & Gold Macaw, the Military Macaw (Green, Yellow & Blue), the Scarlet Macaw (mostly bright red), and the Hyacinth Macaw which is all blue with yellow around the eyes.
How big is the bird? If its an Amazon parrot it could be a red lored, if its small it sounds like it may be a cherry head conure. Amazon - 10" tall (rough) Conure - 6" tall.
It is an Amazon Parrot which can be a variety of color combinations.
Blue and Gold macaw
A parrot
I think it's a parrot.
they have a green head and a blue body.
damselfly
I am pretty sure that the African loon has a green head and a white body.
A mallard is a bird that has an iridescent green head and brown on the body. The ring necked pheasant is another bird with a brown body, and an iridescent green head.
One of the most brightly coloured parrots is the Rainbow lorikeet of Australia. These parrots have a bright red beak and a vividly deep blue to violet head and abdomen. They have green wings and a green tail, and orange and yellow feathers across their breast while the tail is yellow underneath.Other bright parrots include:Sun conuresScarlet macawGreenwing macawEclectus parrot
There is no fish in the world whose head would grow separately apart from the body may be you need to change your question.
Blue bird
It could be a bird in the pheasant family. Ring-neck pheasants have primarily brown bodies with some mottling of colors with a blue to blue/green head. One variation of the ring-neck is called an Afghan which looks like the ring-neck but has no white ring on the neck.
dodo green
If the wing caps are green, it was probably a Painted Bunting. The head color is called blue, but I agree that it looks more purple.