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Blue betta fish: characteristics and genetics for the better selection of matrices

Did you know that there are nuances in the color tone of bettas? That is, blue bettas are different from each other. Red bettas the same way. That is, if you look in detail, you will see that each betta is a betta, even being of the same litter. Fins can be different, color shades, and so on.

What you’ll learn:

Blue bettas genotypes and their characteristics for selective breeding
Metallic bettas
Non-metallic bettas
Bettas carriers of metallic geno
Course on Betta Genetics: techniques to better selection of betta matrices

Blue bettas genotypes and their characteristics

The Bl and bl genes are responsible for part of the definition of the type of blue color in the bettas (other layers of color also interfere!). According to the principles of applied genetics through Punnett Frames, there are three possible combinations of these genes, as follows:

  • Bl Bl
  • Bl bl
  • bl bl

Each of them gives a basic color on the body of the betta. Note, however, that there are four theoretical layers that produce the colors in the bettas, each composing the other, as the case may be.

We’re dealing here with the Iridescent Color Layer.  This layer overlaps with the other layers when active, and these two genes, in the three phenotypes above, initially comprised the genetic modeling of this color. Crosses between different species of bettas resulted in a greater amount of genes defining the colors, color arrangement and shapes of the bettas.

Thus, the current bettas acquired an additional pair of alleles to define the final color of the brightness that will be displayed in the betta phenotype: metallic and not metallic traits. As a result, the three types of brightness, which the bettas could once display, passed to nine different iridescent colors possible.

We, the Betta Project, represent the presence of the metallic trait by the gene * and for the iridescent bettas without the metallic trace (which are the old iridescent bettas, or also called, of traditional, respectively, the blues Royal, Turquoise, and Steel), we use as symbology the gene nm (acronym originated from the initials of the words “non-metallic”).

So there are three possible combinations of these two genes:

  • * *
  • * nm
  • nm nm

Below we show genetic modeling for all possible iridescent colors, involving these two pairs of alleles in the bettas:

The blue bettas genotypes:


Metallic bettas:

Intense Green Royal Metallic Blue OR
Teal Blue

Blue Metallic Steel OR

Traditional Bettas (Non-Metallic Bettas):

Turquoise Royal Blue Steel Blue

Metallic Geno Bettas (Or Metallic Carrier)

Turquoise Heterozygote Royal blue Heterozygote Steel Blue Heterozigote


We treat here the genetic modeling of iridescent colors (also, called structural colors, involving the Genes Bl/bl and */nm.

Added to these two pairs of genes (Bl/bl and */nm) that always work together, we still have the tone of this iridescence (if darker, lighter, blonder or without the black color – the camboja trait).

Want to know more about bettas lineages?

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Interested in learning more about the bettas Genetics?

With this knowledge, you will be able to make better selection of betta matrices to develop traditional or new lineages.

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