Baby Animals
The game says that in order to have babies, you must own two of the same animal. The easiest way to have babies is to adopt a female of any species. Place her in her cage or exhibit and wait about a month of game time. After a month, adopt a male of the same species and place him with the female. The female will become pregnant, and you can select the undo option in the game so you no longer have the male animal.
Easy Money
Enter the game in either campaign or challenge mode. Add water to any location inside your zoo and you will see your cash value rise.
Hyper Children
To make the children at the zoo hyper, build at least ten cotton candy carts in various places. The children will go to the carts and then start to walk incredibly fast.
Ligers
Take a female tiger and a male lion and place them in the same cage. The female will become pregnant and the baby will be a liger (a cross between a tiger and lion). This will also work with a male tiger and female lion.
Repay to Enter the Zoo
To make visitors re-pay to enter the zoo, pick them up and place them directly outside the gate. They will go to the ticket booth and purchase another ticket to enter the zoo. This is especially useful if you are running low on funds. This will only work on people that are actively looking around the zoo. If the character is already on their way out of the zoo, they will not go back to the ticket booth.
White Bengal Tigers
It is impossible to purchase a White Bengal Tiger in the game. In order to acquire a White Bengal, place six regular Bengal Tigers in the same cage. Leave the location and come back, and one of the six tigers will then be a White Bengal.