hmm... I'd try to keep them alive as long as possible, and then have a nice chat with your LFS
and see if they are up for a trade.
Marlin: Okay, a mollusk walks up to this sea cucumber, well he doesn't actually walk, he's just there, and he turns to the sea cucumber, and... Well, wait, there's a mollusk and a sea cucumber and...
Chum: You know for a clown fish, he's not that funny.