This fish appears to be in trouble. When you say you acclimated it, how did you acclimate and for how long?
Did you equalize the salinity in the bag water with that of the tank?
With acclimation, if bor done right can lead to osmotic shock which here may be the case. Fish in shipped bags produce carbon dioxide and ammonia which lowers the pH of the water in the bag, and in turn makes the ammonia toxic to the fish. When you acclimate them, if not done just right, you drive off the carbon dioxide faster than you are diluting the ammonia which then raises the pH of the water in the bag, and in turn makes the residual ammonia very toxic to the fish.