My god just like my striata been beaten by his own sibling (I think). It just took about 3 hours become like this man. I tried to save him but it too late, he is already capsize but still breathing until he died. And my murderer striata already send to brother to keep him solo. Actually he already killed 4 of them and one of them been eaten by him.
You already seperated him right? I think just lower the water level to make him easier to breath. Ask your LFS there any other medication for injury, normally the medicine is in green colour. Hope this help.