Hey, basically I have a 50 gallon tank for 3 baby's wtf there almost 1 yr old and one of them has always been a bit skeptic always over active at night and it seems that he has got that I can describe as black markings, I spose it could be a bruise but on both sides seems suspicious? The markings are around he's eyes Anybody else had previous experience with this? He also acts like he's trying to escape from the tank at night?