Ooooh, he likes that, both the reaction of the fins and the way those hands rub at him. He doesn't like it enough to actually move, mind you, but still.

He huffs appreciatively towards the fins, and it's a good thing there's not much distance for his warm breath to go against them. Humming low in his throat, he continues the soft robbing, concentrating the energy there while letting smaller bits of it beat against the other parts of his gills.