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 "Electric Green", "Sunburst Orange", "Moonrise Pink", "Starfire Red", "Cosmic Blue", and "Galactic Purple" colored tetra (Gymnocorymbus ternetzi) and an "Electric Green" 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. It is sold only in the United States, where it remains the only genetically modified animal to be publicly available. The rights to GloFish are owned by Yorktown Technologies, the company that commercialized the fish.
The original zebrafish (or zebra danio, Danio rerio) 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 fluorescent zebrafish, which Yorktown subsequently branded as "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. 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 March 30, 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. This was followed by the "Electric Green" Barb, which is a variety of tiger barb. In 2013, Yorktown Technologies introduced a "Sunburst Orange" Tetra and a "Moonrise Pink" Tetra, the first fluorescent pink fish to be marketed. This was followed in 2014 by the release of a "Starfire Red" and "Cosmic Blue" 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."
Sale or possession of GloFish remained 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. But it was later removed due to a growing body of evidence and the findings of the Food and Dug Administration and the Florida Department of Agriculture and Consumer Services. GloFish are now legal in California for importation and commercial sale.  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.
Research published in 2014 assessed the environmental safety associated with GloFish. One paper concluded that there is little risk of invasiveness into the environment. A second study concluded that there is no difference in risk between GloFish and wild-type danios.
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).
In early 2014, scientists identified approximately 200 species of naturally occurring fluorescent fish, suggesting that the fluorescence trait is widespread in fish lines.
Other experimental uses
Fluorescent zebrafish also have been used for other experimental research. The alterations in the zebrafish's genes has given the organism the ability to fluoresce as a bio-indicator. This genetic ability has been used to detect pollution and other chemicals.
Chemicals that mimic natural estrogens have well-documented effects on the reproductive systems of vertebrates, typically acting as endocrine disruptors, and GloFish fluorescence is being used to detect levels of estrogenic chemicals. Investigators found that muscles such as the heart have a larger effect of estrogen than the liver. Using the GloFish may thus give insights into endocrine disrupting chemical actions.
The sentiments of aquarium retailers towards the GloFish have also been used as an indicator of the public's reaction to controversial agricultural biotechnologies.
Vulnerability to predation
GloFish are more vulnerable to predation compared to the wild-type, according to a study published in 2011.
In an episode of The Big Bang Theory called "The Luminous Fish Effect", Sheldon makes luminous or glow-in-the-dark fish nightlights, calling it a billion-dollar idea. One of his fish nightlights can be seen in the closing scene of that episode.
In 2011, the Center for Genomic Gastronomy launched the "Glowing Sushi Cooking Show", preparing sushi with GloFish, to raise awareness about genetically modified organisms and explore cutting edge biotechnology.
In November 2013, David Blaine appeared on Live! With Kelly and Michael, spending the entire show in a tank filled with hundreds of GloFish. GloFish also briefly appeared on David Blaine's special "Real or Magic" on ABC, which also aired in November 2013.
- "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.
- "Finformation" (PDF). Greater Pittsburgh Aquarium Society. pp. 4–5.
- "GloFish license".
- "Letter from Director Bonham to Gene Livingston, Greenburg Traurig, LLC, regarding GloFish".
- FDA Regulations for GE Animals
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- "Assessment of the Risks of Transgenic Fluorescent Ornamental Fishes to the United States Using the Fish Invasiveness Screening Kit (FISK)".
- "Risk Assessment of Transgenic Fluorescent Ornamental Fishes to the United States Using FISK v2" (PDF).
- "The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon".
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- Holtcamp, Wendee. "Glow Fish: A New Biosensor to Detect How Environmental Estrogens Affect Tissues." Environmental Health Perspectives 120.7 (2012): a284.
- Peddie, Brian. "A Grounded Theory of Florida Aquarium Retailers' Acceptance of the GloFish" (PDF). University of Florida.
- Jeffrey E. Hill, Anne R. Kapuscinski, Tyler Pavlowich. "Fluorescent Transgenic Zebra Danio More Vulnerable to Predators than Wild-Type Fish". Transactions of the American Fisheries Society. p 1001–1005 .Vol. 140, Iss. 4, 2011.
- "Glowing Sushi Cooking Show". The Center for Genomic Gastronomy. Retrieved 4 March 2014.
- "Glow in the dark sushi made from genetically modified fish becomes the latest food craze to hit America". The Daily Mail. Retrieved 4 March 2014.
- "Troubled waters: fluorescent fish spark GM row" by A. Gumbel, May 4, 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