InsideJapan News Network

Overweight dolphins at a marine park in western Japan have been put on a low fat diet after piling on the pounds.

The aquarian residents of Kinosaki Marine World were put on special rations because they were failing to stay upright while treading water and could not hit jumping targets.

Haruo Imazu, a spokesman for the attraction, commented: "We were puzzled by their poor performance, then we noticed they looked rounder."

When the dolphins were weighted by park keepers, it was discovered that some were up to 22 pounds heavier than during the summer, reports Yahoo! News.

Previously, the dolphins' diet consisted of white fish and mackerel, though the latter has been substantially reduced due to their high fat content.

Kinosaki Marine World is renowned for its spectacular shows and the innovative ways in which it showcases its marine mammals.

The aquarium is around two hours drive from Osaka and Kyoto.