I admit that I say some of the names wrong but without hearing someone saying it it is often pretty hard to know how to prononce it. I mean, how many people do you know in person who know latin fish names? I don't know any, I know them myself but saying them is a bit more difficult.
One thing I HATE beyond hate is when people see anemone fish and call them "Nemo-fish", this bothers the crap outta me. One time at the LFS they had a large oscar for sale, pretty big guy to. A couple of people were looking at it and were talking about how stupid it looked (it was sulking in the top corner) and sitting there making fun of it and pretending to be the fish and saying dumb things. Then one person wondered what kind of fish it was, there was a tag on the tank for a plecostomus...they came to the conclusion that the oscar was a plecostomus.