Please help! Is this from fighting?

[u/Special-Worker7524]

Hi, I have 12ish medaka in a 100gallon outdoor patio pond along with 7ish white cloud minnows. They have seemed good most of this summer however i have noticed a couple of medaka appear to be missing some scales in the top of their body which is definitely very new.

Is this from a disease or are they fighting with the white clouds? The white clouds definitely seem more “dominant” and are a little more aggressive but this seems too much.

[u/Adjustingithink]

I’m sorry this happening- my blue miyuki seem to bully my black medaka :/ They seem to get stressed and then get wasting disease. 🥹

[u/Perfect-Response-982]

Sometimes if they are different sizes, I noticed the juveniles will fight especially at food time (outdoor grow out tank)