6 week old ducklings began to fight

[CloROss]

I have 5, 6 week old ducks. They live outside I have recently bought them a new coop. Today when letting out, I notice one of the ducks had a bleed on its wing and when watching the ducks in the run I have noticed they are fighting. One ran at another pushing it against the fence. The others are just aggressively pecking one another. Out of 5 ducks 2 of them are not doing anything unusual but the other 3 have began this behaviour.

Is this normal? Are they trying to find the leader and show dominance? Or do I need to separate them?

 

[Miss Lydia]

Are they still growing in their wing feathers? That’s pretty typical of them biting on the wing tips when they are growing them in. The fighting doesn’t sound normal for that age how big is their coop and pen do they get any foraging time? Pool time? Do you keep food and water out for them from light to bed time?
What breed/breeds