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Bettas selective breeding

What is selective breeding?

Selective breeding is a technique used for the development of a new variety, resulting from a breeding program.

Interesting to note is the concept of creation: “creation is the applied science of genetics; that is, a fish farmer (aquarist, in our cases) who conducts a selective breeding program is a breeder”.

Figure 1 presents an example of an evolution graph, specifically from the wild wolf to the dogs through selective breeding.

Figure 1 - Evolution of the wild wolf to dogs: selective breeding

Selective breeding in the betta world

According to an article published by the University of Florida entitled ‘Evolution, Culture, and Care for Betta splendens’, the current betta is a product of almost 100 years of selective breeding history.

Initially, males were selected for their aggressiveness towards popular betta females in Thailand - believe me, it is a common practice in that region, just as there are cockfights and other animals around the world.

Today's bettas are very different than the fighting bettas of yesteryear; they have become colorful and beautify our aquariums, this being their main market today.

Still, efforts in its reproduction are totally focused on the beauty of the Betta fish, although the aggressiveness remains.

In the case of bettas, we note that there are some motivators, among others:

  • Commercial advantage over other varieties: occurs when the breeder seeks greater profit from the sale of his breeding stock (when working with Betta fish);

  • Have greater chances of scoring in specialized betta exhibitions;

  • Personal satisfaction as a hobbyist to obtain a new stable and replicable variety.

In figure 2 we represent Betta Azul Royal and Betta Black Devil.

Genetical enhancement

The genetic improvement is the result of fish with certain phenotypes and disposal of fish that do not have them. It is understood that the disposal deals with the purposes for new matings, where the breeder keeps the fish until the end of its life, presents someone with the pet or another destination.

From this selection, the breeder expects a genetically improved fish population. If this happens, the fish of the next generation will be more valuable because their genes will allow the display of a desirable color, color arrangement and / or shape.

In order to carry out genetic improvement, the identification of traits is necessary. These, in turn, are physical expressions of the genes, thus composing the phenotype - which is individual for each specimen, generated by the combination of traits and environmental factors.

See our article “What are lineage bettas” for more information on these concepts.

Genetic management

A breeder who understands why he is doing something is more likely to do it correctly, and that guarantees success.

There are two types of traits:

  • Quantitative

  • Qualitative

Quantitative phenotypes (or traits) are those characteristics that can be measured, such as specimen length, weight, among others. An example of a quantitative phenotype that we see in bettas are the number of rays from the dorsal fin and the number of ramifications of the caudal fin in the bettas, as shown in figure 3.

Qualitative phenotypes are traits (or characteristics) that are not measured, but arbitrated (or judged) in a non-numerical way. Ex: dark / light and colors, such as blue, melano, yellow, red.

In our Course on Betta Genetics, you will learn about a range of traits to analyze and work on your breeding stock and broods for bettas through selective breeding.

Earnings from selective breeding

Selective rearing has proven to be the most effective process for genetic improvement of plants and animals. Specifically, in ornamental aquaculture, it appears that in the 1970s, guppies aroused special interest for selective breeding. It is an easy to reproduce and prolific fish.

In order to give you an idea of how important the selective breeding of specimens is for the purpose of genetic improvement, the figure 4 shows different scenarios that may result from different genetic managements: with selection (selective breeding), wild and poor genetic management (focused on luck), without knowledge.

As can be seen, the lack of knowledge about genetic management results in a decline in the performance of specimen populations - in our case, bettas.


One of the fronts of the aquaculture sector is, precisely, to provide the efficient genetic management of domesticated specimens: and from this emerges the concept of selective breeding.

The management and retention of genetic diversity provides raw material for the success of selective breeding.

Bringing this context to the aquariums of domesticated bettas, it is verified how important is the knowledge of Betta Genetics in order to improve their aesthetic beauty.

We wish you success with your bettas!


[1] Food and Agriculture Organization for the United States (

[2] Aquaculture Europe Magazine – 4th Bimester 2010

[3] WATSON, Craig et al. Evolution, culture, and care for Betta splendens. EDIS, v. 2019, n. 2, 2019.

[4] Betta Project internal archive


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