As the saying goes, there's always a bigger fish. The aim of Zombie Fish Tank is to make sure that that bigger fish is you, which you achieve by eating smaller fish. It's basically the circle of life, but with zombie marine creatures and toxic waste tossed in for good measure.
It's not an original concept by any means - there are hundreds of flash games about leading a little fish up the food chain, and it's a genre that's well catered for on the App Store with the likes of Fish Food Frenzy, Fish Eat Fish, and Hungry Shark Attack to name three.
Here at least it gets an undead lick of paint, and it's layered with the usual accoutrements of the App Store too. There are challenges to complete, power-ups to use, and different fish to buy.
You play a mutated zombie fish beast who has been ripped from his tropical home, had his girlfish squashed, and been tested, poked, and probed by a bunch of mean, biohazard suit-wearing scientists.
Understandably, he's a bit upset, and so he decides the best way to get revenge is to become as big as possible by eating all the other fish in the titular tank. The game is split into levels, each with a size goal at the end.
You control your fish by tilting your iOS device. You can manually reset the calibration by double-tapping on the screen, which really helps if you have to put you iPad down while you're playing.
There are other challenges beyond eating. Some involve grabbing pick-ups, others catching certain fish, or finishing the level within a strict time limit. Every level you complete gives you some currency, which you can spend on adding fish to your fish tank.
Different fish give you different boosts, letting you swim faster or extending the time of your power-ups. You can only have eight fish in your aquarium, meaning you'll need to think about what buffs are going to benefit you most.
There are other clever touches as well, like a poison that reverses your controls, or a weight that hangs around your neck and constantly drags you down. Even the plant life in the various toilets, pipes, and bowls you swim in is out to get you.
While Zombie Fish Tank is by no means an original game, it is at least entertaining. And the extra layers it plops on top of its age-withered carcass mean you never feel too much like you're repeating yourself.
If you can get past that lack of freshness you'll find a fun arcade gobble-'em-up. Just don't expect it to turn you into a fish lover overnight.