Why there isn't an official line of Rapture-inspired fish tanks already is beyond me. Until 2K gets their act together, Super Fan Builds' custom BioShock aquarium shall have to do. No Gods or Kings... only Fish.
Super Fan Builds is a YouTube on Break's Awe me channel that specializes in making fanboy and fangirl dreams come true. So far they've built a Groot swingset and a Hobbit-themed litter box that I would recreate in a heartbeat if it meant my cats would actually use it.
What my cats would use however, is a BioShock fish tank, complete with Big Daddy, Little Sister and Hapless Protagonist. They'd use it like their own personal buffet.
And then one day I would come home and find one of the cats stuck inside. What? BioShock is a dark game, kids.