no i have not noticed any agression in the tank. But might well be that the CK´s fight each other during the night..
but i did a 40% water change and added salt to prevent any further damage to the CK´s...
If the markings are wounds, how long does it take for them to heal ?
Just weird that the red spots are on all the knifes and only on the fins (which are a little messed up)