This is the strategy guide for Adventure Mode.
Tank 1: Treasure Adventure
The first fish you start with are two guppies. Take good care of them by feeding a pellet. If a medium Guppy grows, a Guppy is available to purchase, but you don't have enough money. Get more money from the Guppies. Next, after the Large Guppy, go to the egg to unlock a snail named Stinky.
There's a breed of Alien named Sylvester. Feed the fish and upgrade your food (if you have enough money) Watch out for Sylvester. Attack him by firing at him with your lasers by tapping the screen when you're playing the Delta version or clicking on him when you're on the computer version. In the Mobile version, you must aim him. Keep shooting Sylvester until you send him back to the Netherworld when he explodes. Buy the Egg Piece to get an oyster named Niko.
Here is Niko! Niko is your friend. Every few seconds, Niko will produce a Pearl. It is the introduction of the new fish — the Carnivore. You must purchase one in order to buy an egg. After you have enough money, buy the egg pieces to free a swordfish named Itchy.
Okay, here's Sir Itchy. Itchy is your master. There is a wild merlion named Balrog! Buy laser upgrades if needed to tame this beast back to the Underworld. If you have enough money, buy an egg piece thrice to get Prego. She's a little Breeder.
Pick Prego, Itchy and one more pet. Either pick Stinky or Niko. Prego will produce guppies to get without buying. Carnivores will eat baby guppies, so you don't have to spend your dollars! After you have enough money, buy the egg pieces to unlock a seahorse named Zorf. It's a tank challenge! Collect as many shells as you can. If you have 20,000 shells by doing shell farming, you can purchase an elephant named Brinkley. Time Trial mode is unlocked! Collect as much money as you can. However, you will find many pets you haven't unlocked yet if you buy one.
Tank 2: Mediterranean Spa
Take Zorf, Brinkley (if you purchased him), and Itchy. Zorf will take care of your guppies. There is a star potion, but avoid buying it now. If the big guppies turn green, give one potion to them to produce stars. However, there is no Starcatcher. If you have enough money, buy the egg pieces to unlock a jellyfish named Clyde.
Take Zorf, Clyde, and Itchy. The level is very tricky. Buy a starcatcher to get more money. Starcatchers eat stars. If you have enough money, buy three egg pieces to unlock a skeletal fish named Vert.
When Vert is lame, he gives you less money, a gold coin. Although Vert ain't good, Stars give you more money. Pick Zorf, Itchy, and Clyde again. A wild mermonkey named Gus will come. So, you face a mermonkey, merlion, and before that is the evil Psychosquid! Give him more food to let him explode, since he is immune to lasers. If you have enough money, buy three egg pieces to unlock a fiddler crab. It's Rufus!
Take Rufus, Zorf, and a pet of your choice. You can either pick Clyde or Niko. There is a wild robot named Destructor. Destructor is on ground. Rufus will cut off his body parts until he dies. If he's not dead, he'll fire missiles. Kill Destructor and buy a Starcatcher. Buy three egg pieces if you have enough money to unlock a singing mermaid named Meryl.
Take Rufus, Meryl, and Clyde. The egg is expensive. It costs 75,000 dollars (seventy five what?). Buy some Starcatchers and the tank is tricky. Gus is very tough. Upgrade your food for feeding him. For Destructor, Rufus will do heavy damage. Destroy his missiles and let Rufus cut off his face. If you have enough money, free the little blue whale named Wadsworth. It's a bonus round after that. Get many shells as possible. IF you have enough money, you can free a nosefish named Nostradamus.
Tank 3: The Tank of Japan
Take Itchy, Niko, and Wadsworth. Here is Wadsworth, our blue whale. If any alien is here, Wadsworth will go angry to suck up the small and medium Guppies. He cannot swallow Ultravores, Carnivores, Starcatchers, Guppycrunchers, Beetlemunchers, and Breeders. It's Balrog again. Itchy will cut off his head if Wadsworth has your guppies in his mouth without shooting him. Buy three egg pieces to unlock a sea turtle named Seymour.
Take Seymour, Itchy, and Wadsworth. There is Gus again! Feed him too much food. Seymour will slow down the falling stuff. Look out for a Beetlemuncher. It's a little tadpole with arms and can crunch on stag beetles. Buy three eggs if you have enough money to unlock Shrapnel the Robo Fish.
Shrapnel can be useful but it ain't necessary to use him. Take Seymour, Itchy, and Wadsworth. Look out! There's a moctopus (octopus, squid, monster hybrid) in the way! It's Psychosquid! Psycho will be aggressive. Later, he turns blue. Don't shoot or he'll regain more health. Keep teaching that brat a lesson till he's dead. Buy a Beetlemuncher to get an egg and unlock an anglerfish named Gumbo.
Here's Gumbo the anglerfish! He can only attract Guppies and Breeders, but not anything that's not a guppy. Take Gumbo, Seymour, and Itchy. Watch out! It's Ulysses the Myclops (Mud and Cyclops)! His energy balls can kill all fishes, so you have to deflect his balls and then kill that murderer! Buy a Beetlemuncher and unlock a porpoise named Blip.
Take Blip, Itchy, and Gumbo. Blip will enable all items. Itchy will destroy the two aliens. It's the return of Ulysses and Psychosquid! After you kill them, buy the egg piece to unlock a hermit crab named Rhubarb. You now play a bonus game. You can buy Stanley the Serpent if you have enough shells.
PLEASE NOTE: If you play Time Trial, you can mug your fish with Walter the Penguin if you've bought him.
Tank 4: Davy Jones' Locker
While Rhubarb ain't good, he makes fish die faster. Take Blip, Stanley, and Gumbo. In this tank, guppies ain't purchasable. This is a Breeder. Breeders produce many guppies. Buy a Carnivore and three egg pieces to unlock a manta ray named Nimbus.
Take Nimbus, Blip, and Stanley. Nimbus will bounce objects. Look out for a two-headed skreleton named Bilaterus. Bilaterus will still eat your fish when a bone touches it. Buy a carnivore to unlock eggs. Look out! The most expensive fish is the Ultravore. You can even buy it to make more money, but after alien battles. After buying an Ulravore after the attack, you can buy the egg pieces to unlock an electric eel named Amp.
Amp is awful. Take Blip, Stanley, and Gumbo. Gus is here again with Psychosquid and Balrog. Give Gus tons of food and take down Psychosquid and Balrog. Buy some Carnivores and Ultravores to unlock a fierce shark named Gash.
CAUTION: Gash will eat a Guppy after that. Make sure you got at least one Breeder. Also, don't use Ampy to shock your guppies or you'll waste your money.
Take Blip, Gash, and Amp. If you've bought a pet capacity, take Gumbo. Gash ain't awful. He's just a little shark. There is Destructor, along with Ulysses. Take down both and kill Bilaterus. Gash will do heavy damage and bite their off the aliens' face. (He will also eat your face and your guppies.) After you want more money, you got to purchase more Ultravores. You'll unlock an angelfish named Angie.
Angie is just here. Take her to revive your fragged fish. Pick Angie, Gash, and Blip. If any fish dies, Angie is here to help. This is the final level! Look out for many aliens such as Bilaterus. Buy more ultravores to get more treasure. If you got enough dollars, this egg you bought ain't a pet. It's Dr. Cyrax the Evil Mastermind. Cyrax ain't helpful at all!
Tank 5: Lair of Dr. Cyrax
This is it! This is the final battle with the aliens from the netherworld. There are eighteen pets here. Dr. Cyrax is the traitor! He'll summon some Minisylvester to attack you. There is a random alien after a few seconds. You got to have at least one pet surviving or the battle ain't a victory. Although Itchy, Rufus, and Gash are here, but they ain't helping you because the aliens attack your pets. The best way to let all your pets survive is to find Destructor. LEAVE HIM ALONE! Don't kill him! Deflect his missiles and attack Cyrax until he's no more. Sylvester and Balrog will take at least five hits. Gus is now vulnerable to lasers, but he's a bomb. Destructor is easier than Sylvester and Balrog. Psychosquid is the toughest. Ulysses acts like Destructor, but the energy balls can kill the pets. Bilaterus is annoying. He can eat pets when its bone touches one. Attack Cyrax until you send him back to the netherworld. You unlock a little tadpole named Presto and you will be given tons of shells. The battle is won and you can play Bonus Adventure.