I haven't seen a list anywhere, and since I run an aquatic campaign, I've scanned most aquatic books for one. You don't need one, however. You can just take something out of the MM, such as a snake, but instead of a tiny viper, just call it a sea snake or something. The Improved Familiar feat opens up other options such as Water Elemental, or you could always go custom and go for a tiny octopus or tiny squid just working the MM examples backward.
Pinotage