Answer: GloFish

GloFish, the brilliantly neon variation of the common zebrafish, are a pet store favorite completely irresistible to curious children. Millions of the tiny, speedy, and glowing fish have been sold to Americans over the last decade.

What most of the purchasers are likely unaware of, however, is that the fish aren’t found in nature and, in fact, didn’t even exist prior to a 1999 science experiment. It was then that Dr. Zhiyuan Gong at the National University of Singapore created the brilliant version of the common zebrafish by introducing fluorescent proteins from jellyfish into the zebrafish. Their goal was to create a fish that would react to pollutants in the surrounding water and serve as a mobile and rapidly multiplying indicator of water system health.

While the modified zebrafish have enjoyed success in research settings, their real success has been in the U.S. pet market. Introduced in 2003 as GloFish, the bright green, yellow, pink, and orange fish have become wildly popular. GloFish were the first, and to date only, genetically modified pet approved for sale within the United States.