Legal question:Selling house with built in tank, are fish pets?

[MitchM]

I have commercial real estate experience, and if your aquarium is an integral part of the house (like a dishwasher), then it will be deemed part of the house.
If you're leaving the aquarium anyways, it doesn't have to have fish in it. If you really want to sell the house and the buyers are going to be petty, fill it with freshwater and goldfish.

If the aquarium is a separate unit, stand, plumbing, equipment and doesn't leave any holes in the walls or floors, it's a piece of furniture that you can take with you.

Everything is a bargaining point, either the buyers want the house or they don't.