I have noticed trout on our local streams that have larger heads in proporsion to their bodies, which i assumed were just older trout who live in smaller streams that could be overpopulated.

I have also noted some trout in our streams that have gill plates that do not fully cover the gills. A couple of us think this is some desease the trout has contracted when younger and we think these fish should be killed to prevent the disease transferring to healthy trout. Does anyone know what may cause this?