Can Fish Feel Lonely? Japanese Aquarium Uses Cardboard Cutouts to Cheer Up Sunfish

Have you ever wondered whether a fish can feel lonely? Well, it turns out they can!

The staff at the Kaikyokan Aquarium in Japan were facing a peculiar problem.

An ocean sunfish at the municipal aquarium in the western Japanese city of Shimonoseki was unwell and had stopped eating its meals.

Strangely, the fish’s illness coincided with the aquarium’s closure for renovations on December 1, 2024.

According to a post shared by the aquarium’s page on X (formerly Twitter), the fish had stopped eating its regular meals of jellyfish and was rubbing its body against the acrylic tank.

The handlers of the ocean sunfish suspected digestive and parasitic issues and thought of various ideas to heal the creature.

One staff member suggested that the sunfish might be feeling lonely due to the sudden absence of visitors at the aquarium.

The staff decided to test this theory, and on December 8, they used suction cups to hang staff members’ uniforms on the tank, with face cutouts pasted on cardboard.

Although it looked humorous and childlike, the sunfish started getting better the very next day after this rather funny-looking exercise.

According to a statement by 26-year-old staff member Mai Kato to the English daily, Mainichi Shimbun, the sunfish was popular and a curious creature before the renovations. It would often swim up to visitors when they approached the tank.

When it became a part of the aquarium last February, the ocean sunfish weighed around 61 pounds and measured three feet in length.

The gender of the animal is unknown, and it is tiny in comparison to an adult sunfish, which can weigh up to 5,000 pounds and grow about 14 feet in length.

Found in semi-tropical and tropical waters around the world, the ocean sunfish is one of the largest bony fish in the world.  

Kato added that he hopes more people will take an interest in the sunfish after the renovation work is completed and would love it if visitors waved to it in front of the tank.

The aquarium is set to reopen this summer.