The GloFish is a patented and trademarked brand of fluorescently colored genetically modified aquarium fish. They have been created from several different species of fish: zebrafish were the first GloFish available in pet stores, and recently the black tetra, tiger barb, rainbow shark, Siamese fighting fish, X-ray tetra, and most recently Bronze corydoras have been added to the lineup. They are sold in many colors, trademarked as "Starfire Red", "Moonrise Pink", "Sunburst Orange", "Electric Green", "Cosmic Blue", and "Galactic Purple", although not all species are available in all colors. Although not originally developed for the ornamental fish trade, it is one of the first genetically modified animals to become publicly available. The rights to GloFish are owned by Spectrum Brands, Inc., which purchased GloFish from Yorktown Technologies, the original developer of GloFish, in May 2017.

Genetically modified fish are organisms from the taxonomic clade which includes the classes Agnatha, Chondrichthyes and Osteichthyes whose genetic material (DNA) has been altered using genetic engineering techniques. In most cases, the aim is to introduce a new trait to the fish which does not occur naturally in the species, i.e. transgenesis.