Right, but some people don't seem to realize that there is both a dolphin mamal and dolphin fish. I would say that is probably pretty common for people who don't live near areas with fresh seafood.
Seeing some of the reactions here... just so everyone is aware, dolphin is the real name for Mahi Mahi. Marketing people started calling it Mahi Mahi (the Hawaiian name for it) b/c people were confusing it with Flipper.