The aquarium is a place to display all the fish you have caught. It is unlocked after completing the "Thrilling Aquarium" quest. It contains two floors, one for saltwater, and one for freshwater. These are split even further into a frigid section, tropical section, and temperate section. All sections except the temperate section (which contains three tanks) contain two tanks.
After the island's owner builds the aquarium he asks the player to help him fill it with all kinds of fish. It is said that every fish the player catches is moved to the aquarium, though there is actually a limit to how many of each fish can be seen in the aquarium of a certain species. The more fish in the aquarium, the more visitors there will be. The more visitors there are, the higher the aquarium's profits will be. When the player enters his room at the end of each day, each day's profit will be automatically added to their point balance.
Main Article: Dream Aquarium Tour
Another aquarium featured in Fishing Resort is the Dream Aquarium, featuring nearly every fish in the game. It's an activity and therefore needed to be signed for using the bulletin board.