I would get him out of the tank using the hook and try to get him into a pillow. If you can't go from the tub to the pillow bag first shot because he's too aggressive, try getting him to slither into the pillow on the floor. Once you have him in there, throw in a wash cloth and submerge the pillow in safe amount of luke warm water. I'd say 15-20 minutes, when you go back to check on him he should hopefully be done shedding and in a better mood.

Good Luck

Edit: Just make sure the pillow is a lower thread count and can still allow air to pass when wet.