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Is it Cruel to Keep GloFish?

Psyche Skinner is a psychologist with broad interests in the areas of literature, mythology, and technology.

Is it OK to keep Glofish?

Is it OK to keep Glofish?

Many people are seeing GloFish in pet stores, and naturally wonder whether these fish are hurt when they are made these bright colors or experience poor welfare. You may also encounter these fish in secondary and undergraduate science programs. This article will answer the following questions:

  • How are GloFish created?
  • Does this process cause suffering to the fish?
  • Is their welfare affected in any other ways?
  • Are GloFish dangerous to the environment?

How Are GloFish Created?

GloFish are small aquarium fish species that have been genetically modified to have bright luminescent color. They were first developed to create a more easily visible fish for use in water quality research. The GloFish was first developed in 1999 by Dr. Zhiyuan Gong and others working at the National University of Singapore,

The first GloFish, zebrafish (Danio rerio), were made generally available for sale in 2003. Since then, GloFish varities have been developed for Black tetra (Gymnocorymbus ternetzi), tiger barb (Puntigrus tetrazona), and rainbow shark (Epalzeorhynchos frenatum).

GloFish are now available in six colors: red, orange, pink, purple, blue and green. However the blue variety does not have the vivid glow of the other types. They can be purchased from an authorized seller in the United States (excluding California) but their sale is restricted in Europe, Canada and Australia.


Does this Process Cause Suffering?

There are processes that hurt and damage fish, such as injecting dye into their bodies. However, possession of the "glow" gene is passed from parent to offspring, and causes no discomfort to the fish. Thus there is no need to avoid these fish for reasons of animal welfare.

In contrast, fish that are physically injected with dye ("painted" fish) often experience health problems and discomfort as a result—these fish should never be bought.

Are They Affected in Other Ways?

This is a subject that I do not have an objective data on. However, I have observed that when GloFish and wild type danio (zebrafish) are kept in the same tank, the GloFish age quicker and die younger. By "age quicker," I mean they show reduced vigor, a loss of muscle mass, and bending of the spine at a younger age than the non-modified fish.

This may reflect the increase metabolic burden of being brightly colored and luminescent—leading to the animals being under a greater strain and thus more prone to deteriorating health as they age.

Black tetra (Gymnocorymbus ternetzi)--glofish vatiety

Black tetra (Gymnocorymbus ternetzi)--glofish vatiety

Are GloFish Dangerous to the Environment?

Some commentators worry that GloFish are not well-regulated. They are concerned that these fish might be released into the wild (Knight, 2003).

The risk associated with this species should be limited, as they are intended to be infertile. However multiple aquarists have reported that their GloFish were able to reproduce. If not between each other, than between normal zebra fish and the GloFish variety.

Cruel or Not?

The keeping of GloFish is not cruel, in that the genes are not a direct cause of suffering for the fish. However, fish without these genes may have an overall better quality of life.

Thus buying these fish is not obviously unacceptable on welfare or environmental grounds, but some people may still choose to avoid buying them as the welfare of non-modified fish is likely to be better.


  • Davies, G. (2014). Searching for GloFish®: aesthetics, ethics, and encounters with the neon baroque. Environment and Planning A, 46(11), 2604-2621.
  • Knight, J. (2003). GloFish casts light on murky policing of transgenic animals. Nature, 426(6965), 372-372.
  • Martin, W., & Biake, A. (2007). GloFish fluorescent Zebra Fish. Carolina Biological: Life Science.
  • Vick, B. M., Pollak, A., Welsh, C., & Liang, J. O. (2012). Learning the scientific method using GloFish. Zebrafish, 9(4), 226-241.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


Sherry Hewins from Sierra Foothills, CA on November 12, 2018:

I used to keep an aquarium, and I got two of these glo fish as a gift from my daughter. I enjoyed them, they were a novelty for me. They did both get sick and die within 2 years, but that's happened with other not genetically modified fish.

I think, in all, the aquarium industry is not very humane. Fish lives are very cheap they are a commodity. Lots of them die in transport, and it just the cost of doing business.

I did the best I could for my fish, and I enjoyed having them, as most aquarium keepers do. So, I don't think having glo fish is any worse than having any other aquarium fish.

Finn from Barstow on July 08, 2017:

Well i used to have fish when I was younger and tried it recently and ended up killing them. I had no idea that goldfish were created. nice article.

Penny Skinner (author) on February 25, 2016:

The GM modifications in animals are still very rare in the public sphere. I struggle to think of any animal available to purchase other than the breeds of glofish. As for ho they look, that is a matter of aesthetic taste. I find many toy breeds of dogs far more offensive because their deformities cause the animal suffering. I think that is more important than how the change in the animal was produced.

Asher Socrates from Los Angeles, CA on February 25, 2016:

Unfortunately modifications are wide spread and not only in fish. Everything has been subjected to this in many ways. I've seen these fish before and they look ridiculous. We should ask ourselves, why do we all allow profit to change the balance of the way life and nature were intended?

Blackspaniel1 on March 01, 2015:

I have never heard of this before. Thanks.