Betta Fish Genetics 101: Science Behind Breeding Colorful Bettas

Betta fish are vivid creatures. They are resilient and intelligent too, but the first thing you notice about this beautiful species is their vibrant, diverse color patterns. It almost seems as if you can Betta fish of every color in the spectrum, but don’t let the wide availability fool you. Breeding one with your desired color can be a surprisingly complex and involved process.

Betta Fish have 4 color layers within their skin, and many alleles can influence the dominant color in each layer. The interaction of these color layers mainly produces the color that your eyes see. However, the scales on top of a Betta’s skin can also have variations, resulting in altering or completely blocking the color that these layers produce.

In this article, I’ll explore these color layers and their respective alleles in depth. I’ll proceed to provide brief explanations of the most available color variations that can be found in Betta fish. Finally, I’ll conclude with a simple explanation of how you could use the knowledge here to your advantage.

4 Key Takeaways

The 4 color layers that create the Betta fish’s final color are called the yellow, red, black, and iridescent layers in order.
The yellow layer has no influencing alleles.
The scales on a Betta fish can be opaque, thick, metallic, or clear.
Colors such as black, orange, green, and white and their variations are very hard to attain.

The 4 Color Layers

In order, these are the 4 color layers that exist within a Betta fish’s skin.

Yellow.
Red.
Black.
Iridescent.

Aside from these color layers, the scales on the Betta fish also provide an additional alteration to the final color. However, we will focus on the 4 color layers first, as their interactions produce the vast majority of the possible colors you can find on a Betta fish. We’ll be discussing the genes in these layers by the colors they produce, not by which are alleles of each other.

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1. The Yellow Layer

The yellow layer is the deepest layer for domestic Betta fish. The yellow-pigmented chromatophores responsible for this layer are called xanthophores. There are currently no known genes that modify the color produced by this layer. Most wild Betta fish will have this layer dominate over its upper color layers.

However, there is heavy debate as to why this shouldn’t be considered the yellow layer. The yellow coloration can come from the red color layer on top of this existing one. Some consider this to be the cellophane layer instead, which is exposed in Koi Betta fish’s fins as a transparent, perhaps slightly yellow color layer.

2. The Red Layer

The red layer is controlled by red-pigmented chromatophores called Erythrophores. This layer is controlled by these genes.

Extended Red: This gene will cause the whole body of the Betta fish to be covered with a red coloration. The red color will spread to the fins, which is an attractive trait. The genes responsible for causing this effect are termed Er. The distribution of the color will vary, with rr alleles used to denote lesser distribution while R_ shows more spread.
Non-red: The non-red gene will remove the red coloration entirely from the layer, leaving it transparent. This gene is marked as nrnr, and it is completely recessive.
Yellow: If the nr1nr1 recessive gene is found in the Betta fish’s DNA instead, then the red layer will have a variation of yellow color instead. There are 3 types of yellow that this gene can produce. The common 2 variations are lemon yellow and butter yellow. The rarer 3^rd type is a golden color, which seems to come from the nr1 gene expressing itself over the Er or extended red gene.
Orange: The nr2nr2 recessive gene causes the red layer to develop an orange color instead. Ideally, this gene will create a rich pumpkin yellow color. But interestingly, cross-breeding orange Betta fish will result in a washed-out color. As this gene is recessive, this means the difficulty of commercially breeding them increases significantly.
Variegated Fins: This gene creates the butterfly pattern on the body of the Betta fish. This will create a solid color layer that will extend to the base of the fins of the Betta fish. The fins will have varying patterns of color seeping into them, and the intensity of the colors will vary. This dominant gene is denoted by Vf.
Red Loss: Red loss genes cause the Betta fish to lose color over time. This dominant gene has two alleles. If the Rl_ allele is present, then the fish will lose its red color as it ages. However, the rlrl allele will have no impact on the coloration.

It should be noted that the yellow and orange color-producing recessive genes are alleles.

3. The Black Layer

The black layer’s coloration comes from the black pigments known as Melanophores. This layer is modified by the following genes.

Melano: The Melano genes are genes that create black coloration on the Betta fish. The normal black coloration is represented by a dominant M_ allele, which will create a less intense black coloring or have no black color at all. However, the Melano black allele mm will create a full black layer instead. This allele is rarer, and female Melano Betta fish will be infertile.
Cambodian: The Cambodian genes are recessive genes that cause the Betta fish to have a lower count of melanophores, and the body to be less dark than the fins. The Cambodian allele cc is responsible for this effect. The non-Cambodian allele C_ on the other hand does not affect the coloration.
Blonde: The blonde genes are responsible for creating lighter shades of black, such as pastels or greys. These genes are recessive. The blonde allele bb causes this effect to happen, while the non-blonde allele B_ caused no change in coloration.

Most discolorations in the black layer are best expressed in red Betta fish, which is the immediate layer. However, you can also see such effects with a color on the upper layer. Areas of the skin with lower black pigment will have a shadowy hole effect or allow the red layer to come through more clearly.

gorgeous colorful betta fish — owner: Gabrielle Perry

4. The Iridescent Layer

The iridescent layer is the blue layer and the uppermost color layer of the Betta fish skin. This layer’s color is derived from the blue/green pigmented guanophores. I’ve mentioned the genes responsible for the modification of this layer below.

Blue Color: There are 3 outcomes in terms of coloration that the alleles of this color layer can produce. The BlBl genotype will produce a blue-green color, and this color will only come from full dominance. Incomplete dominance through Blbl will instead produce a royal blue color. And blbl or full recession in the genotype will produce a steel blue color.
Spread: The distribution and density of guanophores in this layer are controlled by these genes. Si_ is the dominant allele, which will cause all or most of the Betta fish’s body to become covered with blue color. The sisi allele will instead cause the Betta fish to have a color reduction, resulting in either lines, dots, or shimmering across the fish’s body.
Non-blue: While the non-blue effect has been seen, there haven’t been any genes identified as the cause for this phenomenon. This will remove the blue color from the layer of the Betta fish.

The black layer plays a large part in how rich the color produced in the blue layer looks. If the black layer has more melanophores, then the blue layer’s final coloration will look dark. Fewer melanophores will result in more pastel-like colors.

The color produced by these 4 layers is modified one last time by the scales of the Betta fish, which I will now discuss.

The Scales

The scales of a Betta fish are the final modifiers that alter the color. Depending on the nature of the scales, they can completely block off or preserve the color produced by the skin layers. Here are the possible variations that you might see on a Betta fish.

Opaque Scaling: Betta fish with opaque scaling will have white powdery scaling. This will cover up the majority of the color generated by the skin layers. These fish can be either steel blue, green, or blue opaque underneath. Steel blue will produce the whitest Betta fish, while the other colors will only be able to seep through a little.
Transparent Scaling: This type of scaling is typical of Betta fish, and it allows the color produced by the skin layers to come through.
Copper Scaling: Copper scaling is the most common variation of metallic scaling that a Betta fish could have. There is a dull copper to most Betta fish with such scaling, although blue Betta fish will show less intense effects. The scales will allow the color to come through but darken and dull the final color.
Dragon Scaling: Betta fish with dragon scaling will have prominent scales that will have a shiny, metallic coloration with darker edges. Dragon scales allow the color from the skin layer to come through but increase the saturation and brightness of it. Each scale will also reflect any light, causing the scales to have an additional metallic sheen.

I’ve detailed the biological factors that affect the color of a Betta fish, but this does not account for the rarer or more complicated cases of Betta fish color patterns. There are outliers and rare variants of Betta fish that have colors that even experts have a hard time understanding. So, we’ll be tackling some of these possibilities next.

Exploring 15 Most Betta Fish Color Variations

These are the possible color variations that you’ll find in both wild and artificially bred Betta Fish.

Solid Red.
Black.
Steel Blue.
Green.
Royal Blue.
Cornflower Blue.
Turquoise.
Yellow.
White.
Chocolate.
Orange.
Marbling.
Cellophane.
Albinism.
Gold.

I’ve covered mostly everything here and explained how each variant of Betta fish gets its colors. There will likely be other color variations. But the knowledge provided here should help you in deducting the genetics or cause behind the coloration.

1. Solid Red

Solid red Betta fish have a bright, bold red color spread all across their bodies, with no signs of fading or iridescence.

Solid red-colored Betta fish are noniridescent, meaning that the topmost iridescent layer expresses non-color genes to let the extended red genes come through. While a fully red Betta fish is desired by everyone, many Betta fish have some splotches of iridescence and other colors. Opaque scales will also mute the red color and turn it into shades of pink and muted red.

2. Black

True black betta fish resemble the color of the Black Mollie fish. Most black Betta you’ll find on the market are closer to shades of smoky grey and light black.

For a Betta fish to be truly black, it must have the recessive Melano black mm gene, and its other layers must have non-color genes to become expressive. This is hardly ever the case, as most black Betta fish will have other active color layers and opaque scales that will cover up their blackness.

On top of this issue, true black Betta fish come from the expression of a recessive gene, and female black Betta fish are infertile. Breeding true black male Betta fish with lighter shades such as black lace will produce infertile offspring, while breeding with other colors such as royal blue or steel blue will introduce iridescence.

gorgeous betta fish over brown leaf — Owner: Holybull79

3. Steel Blue

Steel blue Betta fish, also known as metallic blue Betta fish, has a metallic sheen over its light blue coloring. This is due to the Betta fish having metallic scales covering its blueness.

Steel blue Betta fish are the result of the blbl gene expressing itself in the iridescent layer. Steel blue variants are quite common when breeding Betta fish of blue shades. Breeding 2 steel blue Betta fish will produce all steel blue offspring, but mixing with royal blue will result in 50% of them being steel blue only. Breeding only royal blue Betta fish will also produce 25% steel blue Betta fish.

gorgeous blue betta — owner: Jenna Marder Grenier

4. Royal Blue

The ideal royal blue Betta fish has a dark-colored head, with a royal blue body, fins, and tail. More common variants of this color have some form of green and red showing on their skin.

The royal blue Betta fish are the result of the Blbl or blBl genotype being expressed. They are harder to breed en masse compared to steel blue Betta fish. Whether bred with green, steel blue, or another royal blue Betta fish, only 50% of the offspring will be royal blue in color.

5. Cornflower Blue

Cornflower blue Betta fish have a dark head as well, but they have a lighter, powdery, cornflower blue coloration on their bodies.

Cornflower blue Betta fish also have the same genotype as royal blue Betta fish. Their color variance can be caused by opaque scales, which hide the intensity of the iridescent layer.

6. Green

Green Betta fish possibly have the largest uncontrolled variation in shades from generation to generation. You will find green Betta fish from the deepest shade of green to the lightest be born in each generation seemingly without any pattern. Most green Betta fish will have a bluish-green hue, and true forest green Betta fish will be very hard to come by.

Controlling the color variance in green Betta fish is quite difficult, as all shades derive from the BlBl gene. However, breeding green Betta fish is not as difficult as controlling the shade. Green Betta fish will only produce green offspring. Even breeding green Betta fish with royal blue Betta, or only royal blue Betta will yield 50% to 25% of the offspring being green.

7. Turquoise

Turquoise Betta fish have tones of blue over their light green coloration. It is the most common shade of green Betta fish found, but its shimmering color is considered to be quite attractive.

Turquoise can be considered as the expected expression of the BlBl gene. Although green Betta fish parents will produce turquoise Betta fish, the chance for lighter, blue-toned turquoise Betta fish increase from breeding green Betta fish with either steel blue or royal blue variants.

8. Yellow

Yellow Betta fish can have shades ranging from bright yellows such as lemon yellow to paler yellows such as butter yellow. Yellow Betta fish with even paler complexions or a brown tinge can be found, although they are not as desired.

The nr1nr1 gene in the red layer is responsible for creating this color variation. The yellow layer may also contribute to its color in some fashion, but there is no information or evidence for it. Some yellow Betta fish will also have a golden yellow operculum, which is the layer covering the gills.

gorgeous white betta — Owner: Jessica Spivey

9. White

White Betta fish are very coveted due to a pristine white color covering their entire body. They possess an ethereal quality to them that draws enthusiasts in.

Fully white Betta fish have non-color genes that express themselves in their genotype, along with a fully opaque scale layer that suppresses any color being expressed by the skin. These betta fish will typically have black eyes, although some will have white clouding that tends to get passed on. White Betta fish are hard to breed, as pairing them with any color variant risks creating a generation full of colored spawns.

10. Chocolate

The chocolate variant appears to be brown, which ranges from darker to yellower shades. In reality, darker yellow colors mixed with black give off the illusion of the color.

Chocolate Betta fish require either the yellow nr1nr1 or the orange nr2nr2 gene to express itself in the red color layer, along with a dark shade of black expressed in the black color layer. Curiously, the coloration of both yellow and chocolate Betta fish can be improved if they are bred together.

11. Orange

Orange Betta fish come in a wide variety of shades, from light orange tinges to intensely orange bodies. Some can have marbled bodies, while others have splashes of iridescence. Aside from their lovely colors, orange Betta fish are also prized for their rarity.

The orange color typically results from either the nr2nr2 gene expressing itself, or from a mutation of the extended red gene. Its rarity ensues from orange Betta fish never breeding true. Breeding orange betta fish typically results in either yellow or red offspring.

rainbow color marbling betta fish — Owner: Frankie Hernandez

12. Marbling

A marbled Betta fish will show patches of different colors on its skin. These patches will appear and disappear throughout their lifespan and change color over time.

This phenomenon occurs thanks to a transposon, or a jumping gene called the marble gene. This gene can change its position in the Betta fish genome, causing different pigments to activate and deactivate at different parts of the skin. This gene is marked as MBmb, and the patterns it will produce are considered to be unstable and unpredictable.

cute betta fish close up — Owner: Michelle Smith

13. Cellophane

Cellophane or clear Betta fish have no color on most of their bodies. These Betta fish are almost translucent, and in rare cases, you can see their internal organs in bright light. They are coveted for their hypnotizing beauty.

Cellophane Betta fish will likely carry a combination of recessive non-color alleles that will remove the color from their yellow, red, and iridescent layers, along with the dominant Melano allele which will remove any black color. There may be slight coloration left, but it will only seem that the fish has been tinted.

14. Albinism

Albino, or true albino Betta fish are so rare that many experts will deny the existence of one. It’s easy to mistake a cellophane Betta for to be an albino one. However, a true albino Betta fish will visibly have no pigmentation at all, even in its eyes. Unlike a cellophane Betta fish, its eyes will be either pink or red due to no colors hiding its blood vessels.

Albinism is a condition that inhibits the production of melanin in Betta fish, causing it to have no pigments at all. Other than the eyes, there are prominent tells that give away its nature. Albino Betta fish will have little to no protection against harsh lights and the sun, and they will be prone to a lot more health issues compared to cellophane Betta fish.

15. Gold

Gold or orange Betta fish are rare, and notoriously hard to breed. It is possible to breed orange Betta fish, but most have a faded, washed-out color to them. Only a rare few truly possess the deep, rich, vibrant, golden color that people seek.

As I have mentioned before, the nr2nr2 recessive gene in the red color layer is responsible for producing the rich golden color of these Betta fish. However, breeding Betta fish with this gene will almost always result in color deviations. This is caused by either partial dominance, environmental factors, or other recessive genes.

Conclusion

Understanding how these layers and scaling influence the colors of the Betta fish will aid you greatly in breeding your own. You can now plan which parent fish you’ll need to eventually breed the Betta fish that you desire. But you’ll also need to learn about generational breeding and Punnett Squares to comprehensively understand Betta fish breeding. I’ve already talked about it in a previous article, which you’ll find here.

If you want to explore more, you can always look into generational breeding. Expert bloggers and hobbyists catalog their breeding attempts generationally and can provide you with an accurate description of their chosen genotypes. And if you can’t find what you need, just ask. The Betta fish enthusiast community is surprisingly friendly, and almost anyone would be glad to help.

Betta Fish Genetics 101: Science Behind Breeding Colorful Bettas

4 Key Takeaways