The opening of the aquarium was triggered by the fact that tourists visiting Mikimoto Pearl Island saw the fish tank of Marukou Suisan (a marine products wholesaler that handles high-end fish) on the opposite shore when they crossed to the island by boat, and came to visit on their way home.

The plan to open an aquarium was proposed in response to this, and since it was the same year that Toba was incorporated as a city under the slogan "Marine Tourism City," and the first mayor, Kokichi Nakamura, and the president of Marukou Suisan were close friends, the plan proceeded smoothly, and on May 15, 1955, Marukou Shoten opened the 26th aquarium in Japan The admission fee at the time was 20 yen.

Nakamura was told by Keizo Shibusawa, "Develop the aquarium into a good aquarium, and when profits increase, return the profits to academic research and social education," and he took these words to heart and realized them as described above.

Then, due to the declaration of a state of emergency, the museum was temporarily closed again from April 10 to May 17, 2020.

[citation needed] The aquarium hosts scholarly investigations as an adult education institution in conjunction with the Ministry of Education, Culture, Sports, Science and Technology officially specifying the Toba Aquarium as a museum.

Toba Aquarium also emphasizes protection and breeding of rare marine creatures which are in danger of extinction.

The museum also focuses on the protection and nurturing of rare marine life in danger of extinction, and holds the world records for the birth of a baby snapping turtle and Japan's first second-generation sea otter, the world record for dugong breeding at 11,475 days (31 years and 5 months), and the world record for nautilus breeding.

The male dugong Junichi, who had broken the world record, died on February 10, 2011 at the estimated age of 33.

Commerson's dolphin "Stella" has been in captivity for 22 years and gave birth on June 21, 2023 at 6:42 AM, her fifth case.

[22][23][24][25][26] The shell had been whitening and showing signs since the beginning of the year, and we were able to confirm that the molt had begun early in the morning of the 12th, and were able to photograph and record the process.

1, who fasted for a long period of time, was broadcast live on niconico, temporarily taking down the Toba Aquarium's server.

[32] Initiated by a senior staff member of the aquarium, the ceremony will be held for the 13th time in 2019; in 2020, viewing will be limited to approximately 30 relatives of new employees and general visitors to prevent the spread of the epidemic of new coronavirus infection.