Sunshine International Aquarium, located atop the Sunshine City building in Tokyo's Ikebukuro district, will close for a year beginning Wednesday for large-scale renovations to compete better with other aquariums in the Kanto region.

When it opened in 1978, the aquarium was touted as the first in Japan to be build on top of a high-rise. In recent years, the aquarium has suffered a decline in visitors as rival venues opened.

"If we don't do anything to improve, we won't be able to survive," an official said. The renovation will be extensive, including replacing tanks and improving displays, the official said.

The aquarium has attracted about 35 million people since it opened.

With aquariums in the region rare, its popularity surged soon after opening. In the second year, it attracted more than 1.3 million visitors.

The number peaked at 1.7 million in 1985, when the aquarium began to display sea otters.

Beginning in the latter half of the 1980s, competitors came along, including Tokyo Sea Life Park located in Kasai Rinkai Park in Edogawa Ward and Yokohama Hakkeijima Sea Paradise.

As the competition intensified, Sunshine aquarium's visitors dropped to some 700,000 last year, less than half of its peak.

"By making it easier for visitors to look at a ray's face when it is fed, for example, we would like to make the aquarium more attractive to adults and more satisfying for people who are intellectually attracted to marine life," spokesman Kiyoshi Miyajima said.