Have you ever seen a mudskipper?

It is indeed a fish, but they look and act a bit more like a lengthy frog or ribbon-like salamander. They're found in swampy areas in a number of Southeast Asian countries and, once you've seen one, they're pretty hard to mistake for anything else!

Here's one I spotted on the banks of the Mekong, just west of Ho Chi Minh.

The mudskipper is certainly a fish, but they survive out of water and their little leg-like fins give them a more frog-like appearance