What does a old wife fish eat?

This is a play on words! "Old wife" is a type of fish, not a married woman.

Here's why it's funny:

* "Old wife" refers to a type of fish, often called a "wrasse".

* "Old wife's tale" is a phrase for a story or belief that's considered outdated or untrue.

So, the joke is that an "old wife" fish would eat the same things as any other wrasse, but because it's named after an "old wife's tale", it makes it seem like the fish has some unusual diet!

Let me know if you'd like to try another joke!