Can betta fish change gender?

In this post, we will answer the question “Can betta fish change gender?”. We will also discuss how to determine sex in betta fish.

Can betta fish change gender?

Betta fish can change their gender from female to male and generate fertile progeny in the process. Bettas that have been reversed grow a teste-like organ that behaves as a gonad and produces sperm that is used to fertilise the eggs of female bettas. In the absence of severe hormonal therapies, however, it is doubtful that this will occur naturally. 

Fish species that change their sex just once in their lives account for 10% of all fish species. During the process, they transition from male to female or vice versa, which takes a few weeks to complete. The inversion happens when there is an imbalance in the proportions of the two sexes in the population. It is used by the species to protect itself.

Betta fish and sex determination

The decorative betta fish has undergone significant evolutionary alterations from the wild, in a way that would bring a grin from (heaven or hell, depending on your religious connections). 

It was discovered via two independent investigations of ornamental betta and wild populations carried out in China and at UC Berkeley that the discovery was revolutionary. Throughout its domestication’s 1000-year history, the ornamental betta has developed a sex gene known as the DMRT1.

Betta fish and the DMRT1 sex gene

The DMRT1 gene has two allele versions: one on the Y chromosome, which is only present in men, and another on the X chromosome, which is found in both males and females. In contrast, male bettas that are not subjected to hormonal treatment have been discovered to have XX chromosomes, whilst female bettas have the male XY chromosome. This study indicates that genes are not the only factor influencing betta fish sex differentiation.

Environment and betta sex determination

According to the findings of the preceding study, betta sex determination is more complex and is impacted by environmental variables. According to recent research investigating the effects of temperature on sex determination in betta fry, larvae reared at temperatures ranging around 82 degrees Fahrenheit generated the largest proportion of male fry, up to 67 per cent of the total.

Hormone induced sex reversal in betta fish females

In a study done in 1988, researchers removed the ovaries from female bettas and administered testosterone injections over nine weeks to the animals. They discovered that the females modified the length of their fins, changed the colour of their bodies, and acquired male gonads. They also display the behavioural features of aggressive males, as previously stated. 

It was discovered that about half of the females had been transformed into men, replete with functional genital organs and sperm production. After they killed the neo males and replaced them with female bettas, three out of eleven spawnings produced both female and male progeny. 

Because the reversed females produced both males and females, the researchers believe that a portion of the betta’s brain is responsible for determining its gender. If you are born female, the sex is maintained by female hormones generated in the ovaries, which are produced in large quantities.

How do differentiate male and female betta fish?

Although male and female bettas appear to be the same when they are fry or adolescents, the distinctions between the two genders become increasingly noticeable as they develop and reach adulthood. When your bettas reach the age of around two months, you should be able to distinguish between them based on the traits that distinguish them from one another. 

Fin length is not usually a good measure to detect a fish’s gender, and certain betta breeds have females with longer endpoints than the normal female. Always look at the other sex features of your betta before deciding that he or she is of a specific gender. 

You should search for the ovaries to determine the gender of your betta. If your betta is in the dark, you may use the flashlight to observe the shadows of their organs by shining them behind them. It is likely that if all you see is a rounded tummy and nothing more, the betta is male, as this is the most common sighting.

Look for a black triangular form that extends down towards the tail; this indicates that you are looking at a female betta fish. The following are some of the other variations between the betta genders.

Male betta fish

Betta fish males have gorgeous flowing ends in every colour of the rainbow. They are known as the “peacocks” of the fish world. Compared to their male counterparts, betta females have short ends and more subdued colourations, making them seem drab. 

Compared to female bettas, male bettas are bigger, having thicker bodies and longer ends. To frighten another male, male bettas grow a decorative beard or operculum, which is a membrane behind their gill covers that they flare when they feel threatened. 

When it comes to behaviour, the male betta stands out as being more aggressive than the female betta. The term “Siamese fighter fish” was not given to the breed because it was adorable and cuddly! Early domestication of the betta breed, similar to the present pit bull breed, was used for a fishbowl form of pit fighting as a sport, similar to the modern pit bull breed. As a result, more aggressive males were selected and bred to improve their combat abilities.

Female betta fish

In comparison to the betta male showboats, female bettas are a bit drab in appearance. They are comparable in length to the males, but they are slimmer in diameter. Although the female also possesses a membrane under her gill covers, this membrane is normally kept under the gills and is not seen. 

A white area at the base of the female betta’s front (ventral) ends is referred to as an egg spot or an ovipositor tube, and it is located at the base of her front (ventral) ends. During the mating procedure, the female makes use of this tube to release her eggs.

Betta fish mating process

When your bettas are ready to mate, the male betta will construct a bubble nest in which he will lure a female betta to join him. During the mating ritual, the male hugs the female as she lays down in a typical Victorian ‘swoon,’ in which she releases eggs, which is a beautiful and intricate display of elegance. 

During this time, after many embraces, the male gently retrieves the eggs while the female recovers and may attempt to consume her eggs. As a result, with these passionate couples, it is necessary to separate after mating.


In this post, we answered the question “Can betta fish change gender?”. We also discussed how to determine sex in betta fish.

If you have any thoughts or doubts, feel free to drop us a comment below!

Frequently Asked Questions (FAQs): Can betta fish change gender?

Is it possible for guy betta fish to produce babies? 

The eggs will be placed in a bubble nest, which will be constructed by the male betta fish. In around three days, the young betta fish will hatch. As the eggs hatch, the male betta fish will keep an eye on them and remain under the bubble nest, collecting any that fall out accidentally. Once they have hatched, the newborns are known as “fry,” and they are quite little. 

Can a female betta pass for a male betta? 

While it is possible to keep males and females together, the likelihood of this arrangement operating properly is low. The only time this should be tried is by professional fish keepers who are well-versed in their field of expertise. If you wish to maintain both male and female bettas in the same tank, a tank divider will make your life a lot simpler in the long run. 

Do fish have the ability to alter their gender? 

Researchers have discovered more than 500 fish species that are capable of changing their sex regularly as adults. Clownfish begin their lives as males and later transform into females, whereas kobudai do the inverse. Some animals, such as gobies, can change their sex on the fly. The transition may be prompted by factors such as age, weight, or social standing. 

Is it possible to keep two female bettas together? 

So, sure, two female bettas may coexist peacefully in the same fish aquarium. Female bettas may get along with various species of fish provided they can form a “pecking order” among themselves. 

Do betta fish become depressed or lonely? 

Betta fish are territorial by nature and should not be kept in the same tank like any other betta fish since they will fight and hurt each other, which will frequently result in death. If they are in a large tank, they are unlikely to feel lonely; yet, they may become bored if their tank is too small.

Is it possible to get my betta fish a girlfriend? 

Betta fish are highly gorgeous and simple to nurture, but they may also be aggressive against other fish, leading many people to ask if a male and a female can coexist in the same tank with no problems. Answer: Yes—but only very shortly.


Can Betta Fish Change Gender?

Badura LL, Friedman H. Sex reversal in female Betta splendens as a function of testosterone manipulation and social influence. J Comp Psychol. 1988 Sep;102(3):262-8. doi: 10.1037/0735-7036.102.3.262. PMID: 3180734.