How to Tell the Sex of a GloFish

Written by marlo peterson
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How to Tell the Sex of a GloFish
You'll have to watch your GloFish closely to determine its sex. (Seiya Kawamoto/Lifesize/Getty Images)

Determining the sex of your GloFish is important if you are trying to breed them or if you just want to pick a gender-appropriate name for your new pet. GloFish are a bright breed of zebra fish that are genetically modified for their colours. GloFish typically come in fluorescent orange, red and green colours. There are a few ways to determine the sex of your GloFish, but if you are still having trouble, consult a pet store or expert.

Skill level:


  1. 1

    Make sure the light in your aquarium is on a bright enough setting to adequately reveal detail in your fish. You will be assessing purely physical characteristics that may be subtle, so you'll want to give yourself the best possible chance to make note of these features.

  2. 2

    Choose a fish to pinpoint if you have an aquarium full of them.

  3. 3

    Notice the colours on its body. GloFish have different coloured stripes that serve to identify whether they're male or female. They typically have a blue baseline stripe colour, with another set of stripes in a different colour that indicate the sex. In addition to blue stripes, males will have gold stripes, while females will have silver.

  4. 4

    Assess the body shape and size of the fish. Females tend to be very round in shape, while males are more slender and petite.

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