A fish tank is a glass container you keep pet fish in. You can also keep turtles, hermit crabs or even mice, lizards, frogs and snakes in a fishtank.
Obviously, if you are keeping land animals in a fish tank you don't fill it with water, you put dirt in the bottom and grow plants. A fishtank with plants in it is often called a vivarium. You usually keep mice in a fishtank with sawdust at the bottom instead of dirt, so you can regularly change the sawdust to keep it clean.
Pis forPiggy bank
A piggy bank or money box is a container you use to store coins, and are usually used by children to save money. Piggy banks can be any shape but are most commonly shaped like a pig. They have a slot in the top to put coins in, and an opening at the bottom to get them out again.