Alien Containment (Subnautica)

The Large Aquarium  is a large, circular aquarium which can house Fauna acquired by the player. It is built using the Builder inside Rooms. In order to get inside of or put fish into the Large Aquarium, the player must build a Hatch on the side. The player can then enter the Large Aquarium and release caught fish into it. Non edible fish can currently only be added by using spawn commands

If you leave two creatures inside the Large Aquarium for long enough, they will breed and another fish of the same species will spawn inside. Eggs can also be placed inside the Large Aquarium. Once the Large Aquarium reaches a population of 10 fish, they will stop reproducing.