Pecking problems

[ebeagle35]

I have 15 3 week old chicks in a large dog cage. Yetserday i came home to find the cockerel's tail feathers all plucked and his rump bleeding along with an easter eggers back bleeding. My husbamd found the two brahmaa' tails plucked clean and bloody.
Yesterday i seperated out the ee and my roosyer, a buff orpington. And now i have run out of space, the two brahmas are in another dog cage together.
i assumed the brooder was to small yesterday and thats why i moved them into the large dog cage.
I want to prevent this from happening to more of my ladies becausw i dont have anymore storing options.
I plan on going to get the blu spray today along with a larger feeder. I would like to prevent any further incidents until the end of the week when they can get out in their new coop. It is currently qaiting for a door and a finished roof.

Here are the breeds
1 barred plymouth rock
2 coockoo marans
2 black australorps
1 buff orpington 1 male buff orpington
4 easter eggers
2 light brahmas
2 colombian wyandottes


I havent read found any of these breeds to be aggressive.

 

[Nupe]

How big is the dog crate? Can you post a picture of their set up. 15 chicks sounds overcrowded. This will cause aggression.

 

[ebeagle35]

Unfortunately I don't have a picture right now. The cage is build for a german shepherd and there are now 9 birds in it.
I didnt realize my husband had taken out the brahmas and the wyandottes. So my victims count is 6 at this point.

 

[Nupe]

They need room to get away from each other. I used a dog crate this spring but for only 4 chicks. By the time they were 5 weeks old, they had outgrown it. Is your dog crate like this one? I think they were 3 or 4 weeks old here.