Yes, it is. Really neat thing to see. I've seen snakes take rodents, birds, lizards, and even other snakes. But never a fish.
I was on the beach in northern/central California failing miserably at getting good shots of birds in flight. Then I saw a snake (looked it up once but have forgotten the species) about four feet long coming off a bluff/dune toward the water. It went into a tide pool and there was some thrashing. Then it slithered out onto that rock and began swallowing. Took a long time to get it down.
Here's another from a different angle...just a bit later:
Felt quite lucky to both have my camera with me and the lens I would have chosen for that shot already attached.