Aza still seemed dubious, but he did flap his little paws a little, licking at the droplets of water clinging to his fur. It seemed his pelt was slightly hydrophobic, and with how fluffy he was, able to trap air between the thick fur, he'd probably buoy very easily on the water's surface.

"Just dunk him in there," Prometheus said, resting his cheek on his knuckles, his hand loosely curled into a fist, "He'll float... I think."

And if not, hey, dragons had massive air capacity for assisting in flight and their elemental breathing. Aza wouldn't drown in the 0.2 seconds it'd take for Hades to fish him out in a blind panic.