A tank is a type of exhibit buildable in both Zoo Tycoon: Marine Mania and Zoo Tycoon 2: Marine Mania. Tanks are used to house aquatic and semiaquatic animals, and for Marine Animal Shows.
In Zoo Tycoon[]

A Bowhead Whale in a tank.
In Zoo Tycoon: Marine Mania, a tank will automatically be created after enclosing a space with tank walls. By default, a tank is filled with Saltwater, though it is possible to empty it and fill with Fresh Water instead.
All fully aquatic animals (indicated by a full water background in their icon) need a tank to be housed, as it is impossible to place them on water terrain. Several items, such as most aquatic foliage, are also only placeable in tanks. Semiaquatic animals (indicated by half water background in their icon) can be satisfied with either water terrain, or a hybrid exhibit with a tank (see below).
If a tank section is deleted, the tank will be emptied, animals put in crates, tank-only objects deleted, and the terrain will turn to sand.
In a tank, terrain and therefore terrain needs do not exist. However, the salinity (fresh or saltwater) and tank depth affect the suitability rating. All fully aquatic animals in the game require a saltwater tank.
Marine specialists need to be hired to care for tank animals, including placing food for them.
Tank walls don't deteriorate with time like fences do. Instead, water becomes dirty, which affects animal health and visibility. A tank filter can be placed next to a tank wall to keep it clean, but it will need to be periodically repaired by maintenance workers.
Hybrid exhibits[]

A Loch Ness Monster in a hybrid exhibit featuring a fresh water tank.
It is possible to create hybrid exhibits (also known as combined exhibits or hybrid tanks), by combining a tank and a land exhibit. This is achieved by lowering a tank wall to the same level as the ground on the land exhibit, which creates a ramp that allows semiaquatic animals, such as sea lions, tigers and crocodiles, to cross from one to the other. In a hybrid exhibit, the tank area counts as either saltwater or freshwater terrain for semiaquatic animals, while land animals ignore the tank, and fully aquatic animals ignore the land. The Zoo Tycoon Marine Mania Tutorial 3 - Combined Animal Exhibits is about creating combined exhibits.
Show tanks[]
- Main article: Marine Animal Shows#In Zoo Tycoon.
Special show tankwalls are used to create show tanks, for select marine animals to perform in shows. These tanks need to be connected to a regular tank, which creates a show gate for animals to pass through, and don't directly allow placement of animals or objects.
In Zoo Tycoon 2[]

View from inside a tank housing Manta Rays and Leatherback Sea Turtles.
In Zoo Tycoon 2: Marine Mania, tanks are also created by enclosing an area with tank walls. This will automatically fill the tank with water of the corresponding biome. It can later be changed by using the biome brush on top of the tank. It is possible to rise and lower both the tank base and its walls, but elevation cannot be edited.
Unlike in the previous game, fully aquatic animals can be placed in any deep water, whether it's surrounded by tank walls or not.
Zookeepers take care of aquatic animals much like they do for land animals. They will need a tank platform, the equivalent of a fence gate, in order to enter the tank.
As in the previous game, water becomes dirty with time, and a tank filter can be placed next to a tank wall in order to keep it clean, also needing periodic maintenance. In first person mode, it is also possible to manually clean water and filters.
Tank walls cannot be destroyed by any animal, so it is possible to use them as indestructible fencing. Some marine animals are able to jump over them, though, beaching themselves.
Hybrid exhibits[]
It is also possible to create hybrid exhibits through various methods. The first one is, like in the first game, to lower tank walls until they match the height of the land exhibit, leaving only the curb, that semiaquatic animals can cross. This expansion updated several semiaquatic animals, such as the Emperor Penguin, Polar Bear and Nile Crocodile, to be able to dive underwater.
Because of how water terrain works in this game, it is also possible to create a hybrid exhibit by combining a fence section with a tank wall section and painting water inside the tank wall. By doing this, the water won't register as a proper tank, meaning its base and walls cannot be edited automatically, but on the other hand, elevation can. It is still possible to place a tank filter to clean this water. The Zoo Tycoon Marine Mania Tutorial 2: Hybrid Tank Construction teaches the two methods above.
While the game does not give the option to empty a tank, it is possible to do so by creating a small 1x1 square inside a larger tank, then deleting it. This will remove the water, while the space is still completely enclosed by tank walls. The area inside can later be edited using both the biome brush and elevation tools, thus allowing for things such as a land exhibit enclosed in tank walls, or a "tank" that is fully enclosed and filled with water, which allows elevation editing.
Show tanks[]
- Main article: Marine Animal Shows#In Zoo Tycoon 2.

Show tank (left) connected to a regular tank (right).
Again, special show tank walls can be used to create show tanks for select marine animals to perform in shows. They need to be next to the regular tank, and are connected by show gates.