Hi guys, currently have a 55 gallon which I know long term is overstocked but looking to rehome everything and start a discus tank soon. Anyway recently my Severum has been a bit shy and hiding and I noticed this evident dent above his eye?? He will be rehomed in the next few weeks as I now know it is not suitable. The tank is over filtered and the parameters are all perfect. Is this hole in the head? What can I do to help it? Could it be nipping from tetras or something else. Want to make sure it is comfortable for the next couple weeks and what I can do to help. Other than being a bit more shy, he is acting normally. Thanks