I would suggest a nice sterling silver fish (or not sterling silver - I've a pair of inexpensive japanese fish pendants that I use as earrings) to stand in for a carp. A joke, since carpe means seize, but, hey, a reminder.
I just looked them up - there are lots of koi carp fish pendents online. Mine was much cheaper, if I can find a photo. Turned out that Sozobe had the same fish from a japanese store in her area, and used them for earrings too.
Here's mine - apparently a goldfish -
Huh, $30.00. Mine was something under $5.00, sans a chain.
another one -
This one is a sterling fish, for men -