GloFish® FAQ

Common Questions About GloFish® Fluorescent Fish

GloFish® fluorescent fish are born brilliant! They are not injected or dyed. They inherit their harmless, lifelong color from their parents, and require the same care as any other community fish. GloFish are great for any home, office, or classroom and perfect for hobbyists and beginners alike.

GloFish are similar to other fish, except they have a much brighter disposition. GloFish are available in six stunning colors: Starfire Red®, Electric Green®, Sunburst Orange®, Cosmic Blue®, Galactic Purple®, and Moonrise Pink®.

Today’s GloFish fluorescent fish are bred from the offspring of fluorescent fish that were originally developed several years ago. Each new GloFish inherits its unique color directly from its parents, maintains the color throughout its life, and passes the color along to its offspring.

If you have a question relating to a GloFish branded kit, light, filter, plant, or ornament, please contact Tetra, which manufacturers these products. Their customer service contact page is or you can call Tetra’s customer service directly at 1-800-526-0650, anytime between 7:30am – 5:30pm EST, Monday through Friday.

Want to know more about GloFish? Click on a topic to learn more:

The Science of GloFish

Where do GloFish fluorescent fish come from? GloFish were originally bred more than ten years ago to help detect environmental pollutants. By adding a naturally derived fluorescence trait to the fish, scientists hoped to quickly and easily determine when a waterway is contaminated. The first step in developing a pollution-detecting fish was to create fish that would be fluorescent all the time. Scientists soon realized the public’s interest in sharing the benefits of this research, a process which led to GloFish fluorescent fish.

How common are fluorescent fish in nature? Fluorescent fish are very common in nature. In fact, a recent study conducted by the American Museum of Natural History found more than 180 species of fish that are naturally fluorescent under blue light. Fluorescent fish can be observed expressing vibrant green, red, and orange fluorescence patterns across a very diverse range of species, including more than 50 families. For more details, please click here.

How do GloFish compare to naturally occurring fluorescent fish? As noted above, fluorescent fish are very common in nature. They can be observed in vibrant green, red, and orange colors. As seen here, these colors are strikingly similar to the fluorescence colors expressed by our Electric Green®, Starfire Red®, and Sunburst Orange® GloFish.

What other types of organisms are naturally fluorescent? In addition to fish, fluorescence has been commonly observed in certain types of corals and other marine life, and fluorescence signaling has been reported in butterflies, parrots, spiders, and even flowers.  It has been suggested that they function to assist with things such as visual contrast, antioxidation, photoacclimation, and health. Please click here for more details.

How common is the use of fluorescent fish in science? For almost two decades, fluorescent fish have been relied upon by scientists worldwide to better understand important questions in genetics, molecular biology, and vertebrate development. Fluorescent fish have been particularly helpful in understanding cellular disease and development, as well as cancer and gene therapy.

Where does the fluorescent color come from? GloFish are born beautiful! The fluorescent color in GloFish is produced by an inherited fluorescent protein gene that is passed from generation to generation and creates the beautiful fluorescence that can be seen when looking at the fish. The fluorescent protein genes are derived from naturally occurring genes found in marine organisms.

Are GloFish dyed, injected, or individually altered? No, they are born beautiful!  GloFish® fluorescent fish are traditionally bred; they are not dyed, injected or individually altered in any way. Their unique color is a hereditary trait that is passed from generation to generation, just like any other genetic trait.

How exactly do GloFish help in the fight against pollution? To achieve their goal of helping to fight water pollution, scientists have developed a ‘switch’ that will cause always-fluorescing fish to selectively fluoresce in the presence of environmental toxins. A non-fluorescing fish will signal that the water is safe, while a fluorescing fish will signal trouble. To help further the research, a portion of the proceeds from sales of all GloFish goes directly to the lab where these fish were originally created.

Exactly how do the GloFish become fluorescent? Every variety of GloFish fluorescent fish (i.e., Starfire Red® Danio) began with a single fish. The general process of developing fluorescent fish, as illustrated in this chart (Development of Transgenic Fish), begins by adding a fluorescence gene to the fish before it hatches from its egg. The developing fish will then be able to pass the fluorescence trait along to its offspring upon maturity. From that point forward, all subsequent fluorescent fish are the result of traditional breeding.

How do GloFish compare to their non-fluorescent counterparts? GloFish are like their non-fluorescent counterparts, just with a brighter disposition. They are exactly the same in terms of care, including everything from general care and temperature preferences to water quality and nutritional needs.

Are you going to make other types of GloFish available? New types of GloFish may become available from time to time. Any announcements related to this will be posted on our Facebook and Twitter pages.

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GloFish and the Environment

How long have GloFish been available? GloFish fluorescent fish first became available in late 2003. They have been safely sold throughout the United States since that time.

How can buying GloFish help in the fight against pollution? GloFish have existed for over a decade and were originally developed to help fight pollution. By marketing these fish, we will allow people to enjoy their own fluorescent fish while promoting the beneficial scientific goals behind their development. In fact, a portion of the proceeds from sales goes directly to the lab where these fish were created in order to further their research—research we hope will help to protect the environment and save lives.

Which federal agencies have reviewed these fish? We have submitted detailed information regarding each line of GloFish fluorescent fish to the U.S. Food & Drug Administration, which has jurisdiction over biotech animals, as they consider the added gene to be an “animal drug.” Consistent with the findings of scientists worldwide, the FDA, working in coordination with the United States Department of Agriculture and United States Fish & Wildlife Service, found no evidence that our fluorescent fish pose any more threat to the environment than their non-fluorescent counterparts. (Read the FDA statement regarding our original line of GloFish.)

Have any other governmental agencies reviewed GloFish? In addition to the Federal review described above, our fish have been reviewed by various state agencies, including the Florida Division of Aquaculture. In accordance with the findings of the FDA, these reviews have concluded that our fluorescent fish are as safe for the environment as their non-fluorescent counterparts. To review their specific analyses, as well as those of independent third party experts, please see the GloFish Science section of our website.

What will happen if a GloFish escapes into the waterways? GloFish are tropical fish and are unable to survive in non-tropical environments. Their non-fluorescent counterparts have been sold to aquarium owners worldwide for more than fifty years. Despite all these years of widespread distribution, they are only found in tropical environments. At the same time, please remember that GloFish are intended for use as aquarium fish only, and should never be intentionally released into the wild.

What if a GloFish is eaten in the wild by another animal? For an animal in the wild, eating a fluorescent fish is the same as eating any other fish. Their fluorescence is derived from a gene that is already found in nature and is completely safe for the environment. Just as eating a blue fish would not turn a predator blue, eating a fluorescent fish would not make a predator fluoresce.

Can humans eat GloFish? GloFish, like all ornamental fish, are not intended for human consumption. Accordingly, GloFish should not be eaten.

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Caring for GloFish

Are GloFish freshwater fish or saltwater fish? Like their non-fluorescent counterparts, GloFish are freshwater fish. They should not be placed in a saltwater environment.

Where can I find detailed information about GloFish? GloFish should be cared for in the same way as their non-fluorescent counterparts. In general, guidelines for maintaining a happy and healthy GloFish can be found on our GloFish Care page. A great resource for detailed care information about zebrafish in particular is The Zebrafish Book.

Who can I talk with regarding specific questions about my GloFish? If you have specific questions about your particular fish that are not answered in either of the websites noted above (including concerns about odd behavior or possible illness), our best suggestion is to contact either your local fish store or a local veterinarian who works with fish, since both are great resources for fish-specific questions. If you have additional questions, please visit our Contact Page.

Is my GloFish pregnant? Like their non-fluorescent counterparts, all females will carry unfertilized eggs upon reaching maturity, resulting in a “pregnant” look.

Is there a recommended tank size and/or stocking density for GloFish? Other than the Sharks, GloFish® fluorescent fish are schooling fish. Because of this, they are able to thrive in relatively high densities compared to many other fish. Recommended stocking densities vary depending upon the literature source, tank configuration, filtration system, and other factors, so making a specific recommendation is difficult. We recommend consulting with the experts at your local fish store before starting a new aquarium or adding to an existing community.

What types of fish are GloFish compatible with? Like their non-fluorescent counterparts, our fish are community fish and will “play well” with other fish. However, not all fish are this way, so we generally advise that people check with their local retailer for specific information on whether their existing fish can peacefully co-exist with GloFish. Alternatively, for a partial, but still significant, listing of other community fish, please visit A couple species specific notes; GloFish Sharks can be semi-aggressive, so we advise keeping only one shark per aquarium. They can, however be housed along with other GloFish Tetras, Danios, and Barbs. It should also be noted that our GloFish Barbs can potentially become aggressive if they are not kept in groups of five or more. This is not necessary with our GloFish Danios or GloFish Tetras; while they prefer to be in groups of five or more, they will not become aggressive in smaller numbers.

What should I do if my fish is behaving in an unusual or aggressive manner? Like any other animal, fish are individuals with their own unique “personalities.” While their actions may sometimes seem strange to us, there is a relatively wide variety of behaviors that fish can normally display. However, if you have any doubts as to whether your fish’s behavior is normal, we would recommend contacting either your local fish store or a local veterinarian who works with fish. Both are fantastic resources for fish-specific questions or concerns.

What should I do if I have a question regarding my GloFish aquarium kit? Your satisfaction with GloFish branded products is very important to us. GloFish branded kits are presently all manufactured by Tetra.  If you have a GloFish product manufactured by Tetra, which you can confirm by clicking here please contact their customer service by clicking here or you can call them directly at 1-800-526-0650.

If you have a GloFish® kit manufactured by Koller-Craft, you contact their customer service via email at cservice@koller-craft or you can call them directly at (800) 545-1344, ext. 5200.

If you are unable to resolve your question or concern with these companies directly, please do not hesitate to contact us.

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Displaying GloFish

Do GloFish glow? Fluorescent fish absorb light and then re-emit it. However, they do not actually glow. For tips on the best way to display your fish, please visit the GloFish Display page.

What is the best lighting for GloFish? In general, we have found that blue light (blue wavelength) is ideal, as this can be used in both light and dark rooms. This type of light can be found in most stores that sell aquarium fish. For best results, we suggest using a GloFish LED Aquarium Light.

Where can I buy GloFish? GloFish are sold in retail locations across the country. Please click here to visit our GloFish store locator. Because inventories change relatively frequently, please check with your local retailer for details on availability and pricing.

What colors of GloFish are currently available? GloFish are currently available in Starfire Red®, Sunburst Orange®, Electric Green®, Cosmic Blue®, Galactic Purple®, and Moonrise Pink®. Click here to see an amazing GloFish video or click here to see spectacular photos of our fish.

Are there any restrictions on breeding GloFish or selling their offspring?  Yes. Because GloFish are unique, their sale is covered by a substantial number of patents and pending patent applications For additional information regarding GloFish license details, please visit our License page.

Why can’t I buy GloFish in Australia, Canada, or Europe? At present, Australia, Canada, and Europe prohibit the marketing of any genetically modified organisms, including our tropical fluorescent fish, until they are cleared through an extremely complex and costly review process. For now, due to the time, expense, and uncertainty involved with the approval process, we have no plans to pursue approval in any of these jurisdictions.

Who can I contact about wholesale opportunities? For more information about becoming a wholesale or retail provider of our fish, please send us a message through our Contact page, and we will respond to you as quickly as possible.

GloFish Marketing and Media

Where can I find some photos of GloFish for my publication? Please feel free to use any of the photos posted in our GloFish Gallery. Please credit the photos to It is not necessary to contact us for specific permission.

Who can I contact regarding museum or other exhibition displays? If you are interested in displaying our fish in a public exhibition, we would love to hear from you. Please send us a message through our Contact page, and we will respond to you as quickly as possible.

For more detailed information on the science behind GloFish, please visit our GloFish Science page.

GloFish Ethics

We realize that the enormous potential of genetic technology carries with it an important responsibility. To help ensure that we use this technology appropriately, we are dedicated to the guiding ethical principles outlined in the GloFish Ethics section of our website.

Where to Buy

What stores sell GloFish? Most major pet stores and many independent stores sell GloFish. You can find a store near you with our store locator.

Can I buy GloFish online? Yes! You can order GloFish online and they will be delivered directly to your home. Visit our online store.