1.Georgia Aquarium (6,3 million gallons)
The Georgia Aquarium in Atlanta is the largest aquarium in the world housing more than 100,000 sea creatures. Funded mostly by a $250 million donation from Home Depot co-founder Bernie Marcus, the aquarium opened in November 2005. The Georgia Aquarium is the only institution outside of Asia to house whale sharks. The sharks are kept in a gigantic 24 million liter (6.3 million gallon) tank in the Ocean Voyager exhibit.
2. Dubai Mall Aquarium (2,64 million gallons)
The Dubai Mall, one the world’s largest shopping malls in the world, is part of the 20-billion-dollar Burj Dubai complex in Dubai. The centerpiece of the mall is the gigantic aquarium tank, with the capacity to hold 10 million liters (2,64 million gallons) of water. The aquarium has more than 33,000 living animals including over 400 sharks and rays combined. The panel measures 8.3 by 32.88 meter (27 by 108 feet) and is 75 centimeters (30 inches) thick beating Japan’s Okinawa Churaumi Aquarium to the punch.
3. Okinawa Churaumi Aquarium (1,98 million gallons)
The Okinawa Churaumi Aquarium is located within the Ocean Expo Park in Japan and was opened in 2002. The main tank of the aquarium, called the Kuroshio Sea, holds 7,5 million liters (1,981,000 gallons) of water and features an acrylic glass panel measuring 8.2 by 22.5 meters (27 by 74 feet) with a thickness of 60 centimeters (24 inches), the largest such panel in the world when the aquarium was opened. Whale sharks and manta rays are kept alongside many other fish species in Kuroshio Sea. As of July 2010, there have been a total of four manta rays born in the aquarium.
4. L'Oceanografic (1,85 million gallons)
L’Oceanogràfic is a marine complex where different marine habitats are represented. It is integrated inside a complex known as the City of Arts and Sciences inside the city of Valencia, Spain. The Oceanogràfic features the largest aquarium tank in Europe and houses more than 45,000 marine creatures. They populate nine under water towers, structured on two levels that represent several marine ecosystems. Two underwater towers are joined by a 35 meter underwater tunnel and it’s tank is filled with sharks, rays and 7 million liters (1,85 million gallon) of water.
5. Turkuazoo (1,32 million gallons)
Opened in 2009, Turkuazoo is Turkey’s first giant aquarium featuring a rainforest, flooded forest and tropical seas zones. The aquarium is located inside the Forum Istanbul Shopping Mall and contains a 80 meter long underwater tunnel. Turkuazoo holds about 10,000 sea creatures including tiger sharks, giant stingrays and piranhas in 29 different exhibits where the largest holds 5 million liters (1,32 million gallons) of water.
According to touropia.com