What do mermaids act like?

Well, I have the sims and I know you won't like this, but there aren't really mermaids in the game! You see, to get a mermaid, you have to download one or create one using a program. There are all sorts of possibilities! The one that I first found and it may be the most common, has white shells as a top, and a blue tail with a starfish and fins. But, any other mermaid tail or idea is fine too. Everything else in the sims that you want for your mermaid is optional. such as the hair, skin, etc...