15 x 15 is cutting it a little close as far as chickens space requirements. While I'm sure you can get away with it, there will be a higher incidence of fighting-related problems, possibly like the one now. While you can add pecking blocks, dust baths, or hang treats in their pen to distract the aggressive birds from attacking the birds lower on the pecking order, space will ultimately help with the fighting the most. So that might be something you should consider in the future. Let us know if adding more feeder's/waters, adding things to distract the hens, helps any.I think it is around 15 by 15 ft for five chickens. And yes, I will try adding more feeders and waterers, so thank you for that idea!