According to the BBC, an aquarium store worker and hero known only as Derek, designed and built the little contraption after a customer brought in their sick goldfish. The goldfish suffers from a defective swim bladder, which is the organ that allows fish to control their buoyancy in the water. Without the full control of this organ, they often float near the surface of the water, leaning on their side, or flipping completely over, helpless.
To get the fish swimming again, Derek made an underwater “wheelchair” by wrapping some crimped aquarium hose around the fish, and added a little piece of buoyant styrofoam at the top that keeps the fish upright. He had to experiment with adding just the right amount of weight to the bottom of the rig, but eventually he got the ratio just right, allowing the goldfish a full range of underwater movement.
After images of the build were shared on Twitter by Derek’s friend Taylor Nicole Dean, who often posts educational animal videos on Twitter, the adorable invention led to multiple requests for similar rigs for fish suffering from the same affliction.
According to atlasobscura.com