What do you do when a fish seems down in the dumps? For the staff at Japan’s Kaikyokan Aquarium, the answer was surprisingly simple: cardboard cutouts of people. When the aquarium in Shimonoseki closed for renovations in December 2024, one of its star residents—a sunfish—started acting strangely. The fish stopped eating its jellyfish meals and began rubbing its body against the tank walls. Staff were stumped at first, but one team member had a lightbulb moment: maybe the fish was lonely without visitors. Skeptical but willing to try anything, the team hung up cardboard faces and staff uniforms around the tank. The next day, the sunfish was back to its usual self, swimming happily and even turning its eye toward the makeshift “people.” It turns out this particular sunfish is a social butterfly—or, well, a social fish. Before the closure, it would swim up to the glass whenever visitors came by. Without that interaction, it seemed to lose its spark. Sunfish, also known as *Mola mola*, are fascinating creatures. They’re found in oceans worldwide and can grow to be massive—up to 3.3 meters long and weighing over 1,900 kilograms. This aquarium’s sunfish is much smaller but shares the species’ quirky, bullet-shaped body and long fins. This isn’t the first time Japanese aquariums have gotten creative to keep their animals happy. During the COVID-19 lockdowns, Tokyo’s Sumida Aquarium used FaceTime calls to help shy garden eels stay accustomed to human presence. Who knew a little cardboard and some imagination could make such a big difference? Sometimes, the simplest solutions are the most effective—even for a lonely sunfish.