Finding Dominant Color Traits in Guppies

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Updated on Apr 24, 2017


This experiment explores the most common colors that appear among a sample of crossbred guppies.

Research Questions:

-What are the dominant color genes in guppies?
-Can colors that are not expressed in guppy parents appear in their offspring?


Breeding different types of fancy guppies reveals a combination of traits in the offspring, such as their color and appearance. Guppies are great for learning about genetics because they are affordable pets that are easy to take care of and breed, so you can observe several generations in a short amount of time.


  • Two 5-10 gallon aquariums set up according to directions (including air, filters and substrates)
  • A male fancy guppy
  • A female fancy guppy in a different color than the male
  • Journal
  • Camera

Experimental Procedure

  1. Set up both aquariums. Make sure there are enough plants in one of them, which is where the baby guppies will live and grow.
  2. Place your two guppies in the aquarium with lots of plants, and note the different colors of each guppy and where the colors are located in your journal. It helps to take some photos.
  3. Carefully watch over the guppies for a few days. They should breed quickly, and the female will begin to grow larger.
  4. Once you can see that the female is pregnant, remove the male guppy and place him in the other tank. If you keep him in the same tank, he may annoy the female and eat the baby guppies!
  5. Check the tank for tiny baby guppies, called fry, every day. As soon as you see that they are born, move the mother to the other tank, so she doesn’t eat her fry.
  6. As the fry mature, photograph them and note their color in your journal. This might also change over time.
  7. Analyze your data by making a graph of the number of offspring that resemble their father, resemble their mother, resemble some of both, and neither. The color, or colors, that most common is a dominant trait.
  8. For more research, you could wait for the offspring to grow up and breed some of those to see if the dominant traits still show up. The more data you have, the more accurate your conclusion will be.

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