From level 75 you get the chance to find a nest with valuable eggs on a quest or expedition in the taproom.
Then you can tap the pet icon in the menu's fight category or via the pet building in the city to get to the pets. This will directly give you five of the 100 available pets. The first three pets of each element are randomly generated.
First, pets are limited to three per element - you know them. Known pets can be hatched from eggs which can be found after meeting certain requirements concerning quests or other parts of the game. Eggs you find are displayed wiggling in the appropriate place in the pet area. Tapping an egg will immediately hatch it.
Hatched pets can be fed fruit obtained after winning pet fights, gained from the Wheel of Fortune, as quest rewards or as event rewards. Each pet only likes fruit of its element and can be fed up to a maximum of three times a day.
To discover more pets, you have to defeat a pet in its habitat. Then the next pet is unlocked.
Each element has 20 pets. Pets can be fed up to level 200. Upgrading your pets is limited to level 100 until all habitats have been unlocked.
The pets of each element can compete against pets of another player once per day. Accordingly, five pet fights are possible every day. For each victorious fight you get a fruit of the day. If you lose, the only negative consequence is that you will not receive any fruit.
In expeditions you may get a fruit basket offered to be selected as a reward. On quests fruits can be found with a certain chance, but only if you do not receive an item. When searching for fruits, you should ignore quests with guaranteed items. Certain events offer a higher chance of fruits.
Tapping and holding the name of an element displays how many pets of an element you have explored and collected. Moeover, your pet total is shown.