How to identify male and female Betta fish? 

In this article, we will answer the question “How to identify male and female Betta fish?”. We will discuss the main visual and behavioural differences between male and female Betta fish.

How to identify male and female Betta fish?

It is possible to identify male and female Betta fish by observing the fish appearance, such as colour and ovipositor, and also their behaviour. There are some differences smoother than others, and some might be confusing, such as fins size for example.

However, in general, it is still possible to identify if you consider the multiple characteristics instead of a single isolated trait. Juvenile Betta fish usually do not display sexual dimorphism and thus, are more difficult to determine if they are male or female.

What is sexual dimorphism?

Sexual dimorphism is an expression used regularly to talk about the differences between genders, male and female of the same species.

For Betta fish, in the wild, males and females show weak sexual dimorphism, and this means males and females have smooth differences between them, making it difficult to identify males and females.

Although, captive Betta fish have stronger sexual dimorphism than in nature, which means males and females have more apparent differences, visually and behaviorally.

This difference between wild and captive-bred Betta fish is because, in captivity, Betta fish are selected and bred according to their characteristics, colours, fins, tails, and behaviour.

Morphological differences between male and female Betta fish

Are male Betta fish different in colour from females?

Usually, males have more brightly colouration than female Betta fish. However, colour cannot be the only trait assessed to determine a Betta fish gender. Although male Betta fish are commonly more vibrant in colours than females, female Betta fish can also be very colourful.

Additionally, mature female Betta fish usually display some vertical stripes. However, these stripes can be horizontal while the females are juvenile. They become vertical when the females are ready to mate.

Do males and females have different body shapes?

In general, female Betta fish are shorter and their body wider than males. Male Betta fish usually have more extended bodies and are a bit flatter side-to-side. 

Body shape is a good trait to observe when beginning to sex Betta fish. This is one of the most evident and easy characteristics to identify Betta fish gender. Once you learn the differences, it will be quite easier to differentiate between males and females.

Females are easier to spot than males, especially when they are sexually mature. The easiest part of the body to differ between males and females is the head. Females are rounder and males have a more angular shape.

Do males and females have different fins?

Male Betta fish usually have very long fins, occasionally males’ fins can be three or four times longer than the females’ ones. Caudal fins usually follow the rule. However, in some Betta fish varieties, males have a sporting short caudal fin. The males’ ventral fins are remarkably longer and broader than the females’ ones.

In general, people think every short-finned Betta fish are female. However, there are several Betta fish varieties of short-finned male Betta fish, as well as in nature. Although there are these varieties, in the most common ones, males do have longer and broader fins than females, and you can use this rule when you are sure they are not the short-finned Betta fish. The male’s anal fin is longer, whilst the female’s anal fin is shorter and neater. 

Check for the ovipositor

The ovipositor is the structure female fish use to lay eggs. This structure is exclusive from female fish, and this is no different for female Betta fish.

However some fish may only lower their ovipositor when ready to lay the eggs, the female Betta fish is quite different. Their ovipositor is always lowered and visible after reaching sexual maturity.

To check for the ovipositor, look at the belly of your Betta fish. A little white patch will be visible between the pelvic and anal fins in females. You can opt for using a magnifying glass or a camera zoom to see it.

Betta fish beard

Betta fish have a membrane under the operculum that is called opercular membrane or “beard”. During flaring behaviour, this membrane becomes more apparent as the fish also flare the operculum. Male Betta fish usually have a much longer beard. Female Betta fish have a beard as well, although it is much smaller and less obvious when they are not flaring. When Betta fish flare, the differences in sexual dimorphism become more evident. Female Betta fish may also assume a head-down attitude while flaring, an attitude that male Betta fish do not perform.

Behavioural differences between male and female Betta fish

Siamese fighting fish are the name given to male Betta fish. This is due to their proclivity for being violent against both men and females. They are so aggressive that they can even lower their expected lifespans. As a result, keeping more than one male Betta fish in the same tank is not recommended. Also, keeping males and females in the same tank for the sole purpose of breeding is not encouraged.

Gill flaring behaviour

It is a popular belief that only male Betta fish flare their gills. However, females also perform this behaviour. They flare as a signal of their strength. 

Although, there are few differences between male and female flaring behaviour. Male flaring is a bit more impressive, due to the beard size behind the operculum. The beard makes the fish look even more frightening. 

Aggressive Betta fish behaviour

Females are not as violent as males in general. However, they can also be quite aggressive towards other females and other fish. Female aggression is very stressful, mainly if there are just two females in the tank and they bully each other around. Accordingly, it is recommended to keep a small group of female Betta fish, at least 5 females in the same tank. This is because aggression would not be directed to only one individual, it would be more diffuse.

Betta fish & bubble nest building

In general, only male Betta fish build bubble nests. They blow air in bubbles with a saliva coat that stick together on the surface to protect and provide oxygen to the eggs and babies. However, some females may assist on bubble nest building or during its maintenance. 


In this article, we answered the question “How to identify male and female Betta fish?”. We also discussed the main visual and behavioural differences between male and female Betta fish.

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

Frequently Asked Questions (FAQs): How to identify male and female Betta fish?

Can I keep male and female Betta fish in the same tank?

Except for breeding purposes, it is not suggested to keep male and female Betta fish in the same tank for lengthy periods of time. If you wish to maintain more than one fish in the Betta fish tank, you can choose from a variety of tranquil non-fin-nipper fish.

Should I buy a female Betta for my male?

If you have breeding purposes, you will need a female. However, if you do not have this purpose, it is not recommended, once the male can become aggressive towards the female.

Can I keep two Betta fish in the same tank?

Except while breeding, it is not suggested to maintain two Betta fish in the same tank. However, if you have peaceful female Betta fish, you can house a small group of at least 5 individuals. Less than this could cause some bullying between them and also some stressful situations.

Do female Bettas fight?

Yes, although this is not common to watch female Betta fighting, they can become quite aggressive. If there are two female Betta fish in a tank, they might begin to fight and bully one another. 

What happens if you keep 2 female Bettas together?

If they are very peaceful Betta fish, they can live perfectly together in the same tank. However, if one of them has a more aggressive personality, the situation could become quite stressful, with chasing and bullying.

Why is my male Betta fish running away from the female?

Your male Betta fish may be not ready or comfortable for breeding yet. Before they become closer and more comfortable, this process might take a few days.


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