What is wrong with my keets? ..molting?

i have 8 keets in a newly made 7x5x3 aviary, i made this bec i oftenly see them biting each other thats why they losing their feather, but i watch them carefully in the big aviary their area is somehow ***** too. and everyday i used to vacuum the area, lots and lots of feathers around, is this bec of molting?or too much spreening?or mites, if mites what are the signs and symptoms of having it on them?how can they have this? what to do, pls tell me what is going on to them, they have very nice aviary, people love it but they look ugly, i notice under the body wings, the feather is gone.please tell me, im not happy for them, and can i give them dry oatmeal?thank you in advance.