The GloFish is a patented and trademarked brand of genetically modified (GM) fluorescent fish. A variety of different GloFish are currently on the market. Zebrafish were the first GloFish available in pet stores, and are now sold in bright red, green, orange-yellow, blue, and purple fluorescent colors. Recently an "Electric Green" colored tetra (Gymnocorymbus ternetzi) and tiger barb (Puntius tetrazona) have been added to the lineup. Although not originally developed for the ornamental fish trade, it is one of the first genetically modified animals to become publicly available as a pet. The rights to GloFish are owned by Yorktown Technologies, the company that commercialized the fish.
Early development 
The original zebrafish (or zebra danio, Danio rerio) from which the GloFish was developed is a native of rivers in India and Bangladesh. It measures three centimeters long and has gold and dark blue stripes. Over 200 million have been sold in the last 50 years in the United States ornamental fish market. Despite the number of zebrafish sold, they have never established any wild populations in the United States, primarily because they are tropical fish, unable to survive in the temperate North American climate.
In 1999, Dr. Zhiyuan Gong and his colleagues at the National University of Singapore were working with a gene that encodes the green fluorescent protein (GFP), originally extracted from a jellyfish, that naturally produced bright green fluorescence. They inserted the gene into a zebrafish embryo, allowing it to integrate into the zebrafish's genome, which caused the fish to be brightly fluorescent under both natural white light and ultraviolet light. Their goal was to develop a fish that could detect pollution by selectively fluorescing in the presence of environmental toxins. The development of the constantly fluorescing fish was the first step in this process, and the National University of Singapore filed a patent application on this work. Shortly thereafter, his team developed a line of red fluorescent zebra fish by adding a gene from a sea coral, and orange-yellow fluorescent zebra fish, by adding a variant of the jellyfish gene. Later, a team of researchers at the National Taiwan University, headed by Professor Huai-Jen Tsai (蔡懷禎), succeeded in creating a medaka (rice fish) with a fluorescent green color, which like the zebrafish is a model organism used in biology.
The scientists from NUS and businessmen Alan Blake and Richard Crockett from Yorktown Technologies, L.P., a company in Austin, Texas, met and a deal was signed whereby Yorktown obtained the worldwide rights to market the GloFish. At around the same time, a separate deal was made between Taikong, the largest aquarium fish producer in Taiwan, and the Taiwanese researchers to market the green medaka in Taiwan under the name TK-1. In the spring of 2003, Taiwan became the first to authorize sales of a genetically modified organism as a pet. One hundred thousand fish were reportedly sold in less than a month at US$18.60 each. It should be clarified that the fluorescent medaka are not GloFish, as they are not marketed by Yorktown Technologies, but instead by Taikong Corp under a different brand name.
Introduction to the United States market 
GloFish were introduced to the United States market in late 2003 by Yorktown Technologies, after more than two years of extensive environmental research and consultation with various Federal and State agencies, as well as leading experts in the field of risk assessment. The definitive environmental risk assessment was made by the U.S. Food and Drug Administration (FDA), which has jurisdiction over all genetically modified animals, including fluorescent zebra fish, since they consider the inserted gene to be a drug. Their official statement, made on 9 December 2003, was as follows:
"Because tropical aquarium fish are not used for food purposes, they pose no threat to the food supply. There is no evidence that these genetically engineered zebra danio fish pose any more threat to the environment than their unmodified counterparts which have long been widely sold in the United States. In the absence of a clear risk to the public health, the FDA finds no reason to regulate these particular fish."
Similar findings were reached by the state of California’s Department of Fish and Game and the state of Florida’s Transgenic Aquatic Task Force.
Marketing of the fish was met by protests from a non-governmental organization called the Center for Food Safety. They were concerned that approval of the GloFish based only on a Food and Drug Administration risk assessment would create a precedent of inadequate scrutiny of biotech animals in general.
To prevent this, the group, along with one of its sister organizations, filed a lawsuit in US Federal District Court to block the sale of the GloFish. The lawsuit sought a court order stating that the sale of transgenic fish is subject to federal regulation beyond the FDA's charter, and as such should not be sold without more extensive approvals. In the opinion of Joseph Mendelson, the Center for Food Safety's legal director:
It's clear this sets a precedent for genetically engineered animals. It opens the dams to a whole host of nonfood genetically engineered organisms. That's unacceptable to us and runs counter to things the National Academy of Sciences and other scientific review boards have said, particularly when it comes to mobile GM organisms like fish and insects.
The Center for Food Safety's suit was found to be without merit and dismissed on 30 March 2005.
Developments since the GloFish introduction 
GloFish have continued to be successfully marketed throughout the United States. Since their introduction in late 2003, there have been no reports of any ecological concerns associated with their sale.
In addition to the red fluorescent zebrafish, trademarked as "Starfire Red", Yorktown Technologies released a green fluorescent zebrafish and an orange-yellow fluorescent zebrafish in mid-2006. In 2011, blue and purple fluorescent zebrafish were released. These lines of fish are trademarked as "Electric Green", "Sunburst Orange", "Cosmic Blue", and "Galactic Purple", and incorporate genes from sea coral. In 2012, Yorktown Technologies introduced a new variety of "Electric Green" GloFish, derived from a different species of fish, the black tetra. Despite the speculation of aquarium enthusiasts that the eggs are pressure treated to make them infertile, it has been found some GloFish are indeed fertile and will reproduce in a captive environment. However, the GloFish Fluorescent Fish License states "Intentional breeding and/or any sale, barter, or trade, of any offspring of GloFish® fluorescent ornamental fish is strictly prohibited", thus imposing a legal GURT.
Sale or possession of GloFish remains illegal in California due to a regulation that restricts all genetically modified fish. The regulation was implemented before the marketing of GloFish, largely due to concern about a fast-growing biotech salmon. Although the Fish and Game Commission declined to grant an exception (solely on ethical grounds) in December 2003, it later reversed course and decided to move forward with the process of exempting GloFish from the regulation. However, due to the State’s interpretation of the California Environmental Quality Act, Yorktown Technologies was informed by State attorneys that it would first need to complete a study which could cost hundreds of thousands of dollars and take years to complete. According to the company’s web site, they have thus far declined to undertake this study.
Canada also prohibits import or sale of the fish, due to what they report is a lack of sufficient information to make a decision with regard to safety.
The import, sale and possession of these fish is not permitted within the European Union. On November 9, 2006, however, the Netherlands’ Ministry of Housing, Spatial Planning and the Environment (VROM) found 1,400 fluorescent fish, which were sold in various aquarium shops.
In January 2009, the U.S. Food & Drug Administration formalized their recommendations for genetically engineered animals. These non-binding recommendations describe the way in which FDA regulates all GM animals, including GloFish.
Sources of colors 
Examples of sources of fluorescent protein genes include GFP (Aequorea victoria, jellyfish), GFP (Renilla reniformis, sea pansy), dsRed (Discosoma, mushroom coral), eqFP611 (Entacmaea quadricolor, sea anemone), RTMS5 (Montipora efflorescens, stony coral), dronpa (Pectiniidae, chalice coral), KFP (Anemonia sulcata, Venus hair anemone), eosFP (Lobophyllia hemprichii, open brain coral), and dendra (Dendronephthya, octocoral).
Popular culture 
An episode of The Big Bang Theory called "The Luminous Fish Effect" sees one of the main characters named Sheldon making luminous or glow-in-the-dark fish nighlights, calling it a billion-dollar idea. One of his fish nighlights can be seen in the closing scene of that episode.
- "GloFish web page".
- Gong Laboratory Website
- Published PCT Application WO2000049150 "Chimeric Gene Constructs for Generation of Fluorescent Transgenic Ornamental Fish." National University of Singapore 
- "FDA Statement Regarding Glofish".
- Charles Choi (January 7, 2004). "GloFish draw suit". The Scientist.
- "GloFish® Electric Green Tetra".
- "Finformation". Greater Pittsburgh Aquarium Society. pp. 4–5.
- "GloFish license".
- "GloFish in California". GloFish. Yorktown Technologies. Retrieved 22 April 2013.
- FDA Regulations for GE Animals
- "Regulation of Genetically Engineered Animals Containing Heritable Recombinant DNA Constructs".
- "The Luminous Fish Effect".
- "Troubled waters: fluorescent fish spark GM row" by A. Gumbel, May 4th, The Independent, London, England
- "Frankenfish and the future", by F. Mazyoer, January 2004, Le Monde diplomatique (free in French, Esperanto, Portuguese)
- "Leuchtfische aus dem Genlabor", by M. Robischon, August 2006 Natürlich 8: 6 - 13
- FDA Regulations for GE Animals
- Description of technology required to create glofish and other fluorescent transgenic organisms
- Care information on GloFish
- Dr. Gong's issued US patent
- Dr. Gong's pending US patent application