Erythrinus erythrinus
I acclimated him, put him in a well planted tank with sand substrate (40gB) and he was in there by himself.
The next day, he was running into the front glass, continuously, as if he was attacking his own reflection.
He was relentless, swimming at himself all over the front glass.
He had literally peeled the skin off of his face, and it was flapping around on his nape.
He lasted about 36 more hours and perished. The only time he stopped this behavior is when live food was added.
He seemed normal in the bag and during acclimation. Not sure what to say. Would love to try again.