Well, dolphin for flipping action, or octopus for tentacles. I vote for tentacles.
the shark shall respond to the feast command as if it's name were feast. and i need a name for a female Nixie. preferably something that works with the shackles.
If you're going to spend the whole campaign on ships, then the Aquatic bloodline is certainly worth a look. Getting a swim speed and the ability to breathe underwater are great bloodline powers for this.