A sunfish at a Japanese aquarium found an unusual cure for its loss of appetite after aquarium staff realized it might be feeling lonely once the facility closed for renovations.
A recent addition to the Kaikyokan aquarium in Shimonoseki, southwestern Japan, the sunfish began showing signs of distress shortly after the facility closed in December 2024, according to aquarist Moe Miyazawa.
In a creative attempt to comfort the lonely sunfish, keepers placed their uniforms and human-shaped cutouts with smiling faces outside the tank. The unconventional strategy paid off as the sunfish resumed eating the very next day, for the first time in a week.
"We were skeptical but decided to do anything we could," Miyazawa said, addressing one colleague's suggestion that the fish might be missing its audience.
The sunfish, which arrived at the aquarium in February 2024 from the Pacific waters off Kochi, had quickly become a popular attraction due to its unique appearance and large eyes. Its sudden decline in health following the aquarium's closure on Dec. 1 for a six-month renovation had confused staff.
Miyazawa said the sudden change in health was surprising.
"I knew [the sunfish] was looking at us when we were placing them, but I never thought it would start eating the next day," the aquarist said, regarding the cutouts.
The nonprofit said this species is also notable for its quick growth from birth to adulthood, maturing millions of times larger than when born.
"Newly hatched ocean sunfish weigh less than a gram, and this species is noted for one of the most impressive transformations in size in the animal kingdom," according to Oceana. "The biggest adult ocean sunfish are 60 million times larger than when they hatched."
Despite their massive size as adults, young sunfish face a variety of predators before they reach adulthood.
Oceana reports that "medium-sized individuals are eaten by sea lions, killer whales, and large sharks."
They could even be used as a toy, as "California sea lions are known to bite the fins off of small ocean sunfish and then play with them like frisbees.”
In addition to their astonishing growth, female ocean sunfish produce more eggs than any other vertebrate, releasing as many as 300 million eggs at a time, several times throughout their lifetime.
As the Kaikyokan aquarium prepares to reopen in the summer, keepers continue to visit and wave at their lonely companion during the renovation period.