My birds just recently become aggressive unlike before. They now fight often and the weak ones among them kept on being pecked on. If you separate the weaker ones in another cage they’ll start pecking themselves. How can I solve this problem?
Do they have enough space? Is the temperature too high and is the light too bright? Use red lights at night because it will help prevent fighting. Also, while introducing new hens into the flock, do so at night when it's dark.
In addition, add enrichment in their pen so that they'll have something to explore.
If there is uneven growth, the bigger ones will prevent the smaller ones from eating or drinking. In that case separating them is very important.