Hi, thank you all for replying. It is not pasty butt and they are not getting picked at.
They are all the same age, just about a month old.
I use DE in my coop, sprinkle it liberally around everything, where they dust bath. When I clean out their area I put it on the floor before the bedding.
I have sat and watched and no one is picking at them. They are eating, drinking pooping and just not growing at all.
The skin underneath looks blue??? or black and as you can see covers a large area.
If it is a parasite, should I be using a mite/lice powder??
Or is there something that can be put in the water to help them?