Today I noticed a mark on my oscars head. He is in a 150 gallon tank with a jack dempsy, about 3-4 inches, firemouth, about 1-2 inches and a striped raphael catfish that sleeps all the time. My oscar and dempsy get along fine. My dempsy never attacks the oscar, but the oscar will chase him a little if he comes close when he is eating. Could this be whole in the head? Or somehow could the jack dempsy take a bite out of him?
Here is a pic, I marked an arror for the Sofa King Dumb people.

Here is a pic, I marked an arror for the Sofa King Dumb people.
