Workers at a Tokyo aquarium are scratching their heads after the deaths of dozens of fish that have left just one lonely tuna roaming a once-flourishing tank.
The park on Tuesday found the second last fish floating dead in its vast doughnut-shaped enclosure that was once home to nearly 160 fish and among the venue's most popular attractions, said a spokesman for Tokyo Sea Life Park.
"We have had the tuna tank since the aquarium opened in 1989 but never experienced this kind of mass-dying," he said on Wednesday.
"We are studying what caused the fish deaths, but we haven't figured it out yet. We suspect that it could be due to new factors that were not present before."
Researchers are studying a range of possibilities including the tank's lighting and other factors that could have caused stress among the fish, or even the presence of a poisonous substance in the water, he added.AFP
