Hi, got some pics of the tank?
Depending on the size of the fish, your tank might be a bit on the small side. Aside from that, it’s apart of their natural behaviour to have a pecking order and bully each other a bit. There is obviously a limit though. I started with 6 and now have 10, and the bullying/pecking order is more diluted than what it was when I had 6. I have the 10 fish which are 5-7” in a 650 L tank, with lots of driftwood and plants so everybody kind of gets their own space, even though there are dominant fish/breeding pairs. From my research and experience so far it is a little bit of trial and error.
You can try taking the fish out, rearranging the driftwood/decor and putting the fish back. This can reset the pecking order .
How long have you had the fish?