Happy Aquarium takes your tank on a Tiki island vacation
A good consolation purchase for the Kitten, if you're inclined towards critters, is the cooly animated, drink-sipping, sun-soaking "Happy Turtle", since he's going for 10 FB Credits or 12 Pearls. But I'd much rather buy the "Bubbling Tiki Torches" flanking both sides of the tank, and priced at a reasonable 13 FB Credits or 15 Pearls. Like a lava lamp, you can just stare at them shooting pretty bubbles forever.
Coins can get you everything else, from the "Shell Lounger", to the "Glowing Rock" on the bottom left. I just really want to point out that there are some great special effects going on with the items here. While the "Tiki Torches" have a strong presence, the "Glowing Rock" can also be paired with the "Tall Glowing Rock" to offer a more subtle effect best achieved on a dark background. When set, both are animated to pulse in an eerily florescent green glow.
Finally, the "Tiki Pole" (which looks like a tri-color totem pole and sells for 80 coins) cannot be bought yet, and is currently available as a random item from clicking the Treasure Chests.