I want to put it in an Aquarium. Where should I buy/get one for my special little guppy who shall become a big fish later? ^^

Thanks for answering this silly question.

You need an Empty Aquarium and they can be purchased in user shops, or found at Home Appliances. They have rarity of 50, which means it will show up there sometimes, you will likely have to stalk the shop for a couple of days.

It can be used with an and will create this:

Thanks and !!! ^^