If there were mansions for fish, this would be one of them, a mega fish tank with different "rooms" where your fish can roam at ease. That is Silverfish, a design Octopus Studios which consists of several round fish tanks placed at different levels and connected to each other by tubes (also glass) or passages.
It has a temperature regulator, air pump and capacity of 223 liters of water. They say that fish tanks are relaxing, but in front of this you can spend hours and hours observing how fish move from one place to another. The bad thing is its price: 2345 €.
Further information: octopus