Zombiquarium

Zombiquarium is a mini-game unlocked by beating Adventure Mode and other mini-games in Plants vs. Zombies. In it, the player spends five sun to feed brains (up to three can be in the tank at a time. Also, brains can only disappear by either sinking to the very bottom or if a zombie eats it.) to Snorkel Zombies, which produces sun in turn. The player can also use sun to buy more Snorkel Zombies or to buy the trophy and win the level. The trophy costs 1000 sun. The brains cost five sun. One Snorkel Zombie costs 100 sun. The player has 20 seconds to feed a Snorkel Zombie before it dies.

Strategies
Simply feed the zombies when they get hungry. It shows they are hungry when by turning into green. If zombies have not been fed for 20 seconds, they will die. You should collect sun and occasionally buy other zombies if you feel like it until they have enough sun for the trophy. It is a good idea to keep one brain floating in the tank at all times, as you can tell when zombies are hungry by seeing if they swim towards it.

Trivia

 * This mini-game is based on the game Insaniquarium, also by PopCap Games.
 * It also uses the same sound effects.
 * This is one of the three parts of the game that does not involve any zombies attacking the player's house, the others being the Zen Garden and the hidden Mini-game Ice Level.
 * In some versions, the second tombstone's message RIP is replaced by something that slightly resembles the Orchid Cactus.
 * This is the only place, other than the Zen Garden's Aquarium Garden, that is under the water.
 * The only zombies that are used are Snorkel Zombies despite zombies not needing to breathe, as noted in its Suburban Almanac entry.
 * This may be because they are the only zombies that can swim.
 * This, Whack a Zombie, and Last Stand are the only mini-games in which zombies give Sun.
 * The music played is called "Moongrains" which is the same as the music played on night levels, even though this is not necessarily set in the night.
 * When the player has more than ten zombies, more instruments will play in the music (like when a huge wave of zombies come on a night level).
 * Zombiquarium and Air Raid are the only mini-games that do not take place in the front yard, the backyard or on the roof.
 * If the Zombiquarium save file is modified to another save file, for example, Last Stand, then the player cannot feed the zombies. Instead, if the zombies die, they will drop money, chocolate, diamonds, and Zen Garden plants.
 * This is the one of two times in Plants vs. Zombies which zombies can be purchased via sun, the other being I, Zombie.
 * The Sunny Days achievement can be earned through this mini-game, by not purchasing the trophy and continuing to collect sun.
 * This is one of the two levels without any plants in Plants vs. Zombies, with the other being Zombie Trap.
 * It is a portmanteau of the words Zombie and Aquarium.
 * It is the only mini-game where zombies do not attack player's house.
 * This is currently the only mini-game where zombies do not lose their head when they die.
 * By hacking, you can add other Zombies which will also starve and die.