A lonely sunfish has been given cardboard human friends by staff at an aquarium in Japan to help improve its mental health.

The ocean sunfish, also called a mola, started displaying unusual behaviour in December after the Kaikyokan Aquarium in the western city of Shimonoseki was temporarily shut for renovations.

Staff noted that the previously “sociable” and “popular” sunfish had stopped eating jellyfish and began rubbing its body against the tank.

It was initially suspected that the sunfish could be suffering from digestive issues, parasites or struggling with the sounds and vibrations from the ongoing construction, local newspaper Mainichi Shimbun reported.

Then one staff member suggested the symptoms stemmed from loneliness, prompting a “last resort” intervention of constructing an audience for the sunfish earlier this month.

In a photo posted by the aquarium on social media, the sunfish can be seen swimming past a row of photos of human faces taped to the tank’s glass and placed atop uniforms on hangers to mimic a crowd.