Stop action in low light

Hippos are hard to shoot because usually their heads are barely sticking up above the surface of a river or pond. Pictures of them are exciting only when they are fighting or, in the case of this situation, playing. The problem was that I came upon this pond after sunset, and it was quite dark. The first choice that has to be made when shooting an action shot is shutter speed, and to freeze the water splashes and the movement of the animals I selected 1/500 using manual exposure mode. Had there been more light, I would have opted for 1/000 or 1/1250. I shot this with the largest aperture available on the Canon 100-400mm at full extension -- f/5.6 -- and I let the ISO go to automatic. In this muted light, the camera's meter selected 5000 ISO here. Using Neat Image software in post-processing, I eliminated the noise. As usual, Neat did a great job.