Betta Anatomy (Find Out How Amazing These Fish Are!)

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Last Updated on 2023-05-24

Bettas are fighting fish native to Southeast Asia, where they are known as Siamese fighting fish. A betta fish’s anatomy can be highly intricate. The external anatomy, internal anatomy, and differences between males and females of the species are all unique bodily components to consider. 

Continue reading to discover more about betta fish anatomy and the differences to note between the sexes. 

A Betta Fish’s External Anatomy

First of all, here are the external things you’ll be able to spot on your betta fish, and what they’re used for!

The Eye Anatomy of Betta Fish

Betta fish have two eyes. One on each side of their heads. If you look at your betta, you’ll notice their eyes stick out slightly.

A betta’s iris is black in color and quite noticeable. The color of the outer section varies with the fish.

How Strong Is a Betta Fish’s Vision?

Bettas have excellent vision, as indicated by their flaring personalities that their owners can see. They see everything in full color, even though they don’t have eyelids or the capacity to blink.

Bettas actually have monocular vision, each of their eyes works individually, unlike our eyes that work together.

(Want to know if bettas can see in the dark?)

Anatomy of a betta

Betta Fish Mouth Anatomy

Betta fish have several tiny, sharp teeth in their mouth that help them chew down their food. Their lips are angled upwards to inhale air, build bubble nests, and consume food at the water’s surface.

During mating, males play an unusual function in which they help the female lay her eggs, by wrapping around her and squeezing them out. When they’re ready, the eggs are then added to the bubble nest where your male will then protect them until they’ve hatched.

Opercula on Betta Fish

The operculum of the betta fish works as a defensive mechanism for the fish’s fragile gills. A betta beard, also known as the membrane, can be found here. In male bettas, the operculum protrudes. This makes it the male sex’s more differentiating feature.

Betta fish flares their gills and lengthen their beard while in battle mode. This is a domineering motion used to make themselves appear larger and scarier.

Gill Anatomy of Betta Fish

Betta gills, like other fish, are used to pull out molecules of oxygen dissolved in the water.

Although having a labyrinth organ allows them to get oxygen from above the water’s surface, it’s not healthy for bettas to do this constantly. To only obtain the oxygen molecules using the gills is much more efficient

You’ll even notice your betta sleep underwater that’s how good their gills are!

Betta Fish Body Anatomy

The complete outside of the body is covered in scales apart from the fins, and they can reach a length of more than 2.5 inches. A healthy betta fish will have colorful, beautiful scales.

be warned though, sharp tank items and contact with other aggressive fish can damage the scales as well as the fins and tail. 

When your betta is stressed, you may observe horizontal lines going down their body, these are stress stripes and they should never be ignored. If however, you notice vertical stripes on your betta, then they’re breeding stripes.

What is The Caudal Peduncle?

The caudal peduncle follows the body of a betta and ends right before the back fin, it is the main way bettas push and propel themselves through the water. It ends on the caudal or tail fin, which comes in various forms, sizes, and colors, and is required for water propulsion.

Betta Fish Fin Anatomy

Now you know the anatomy of your bettas body, here is the anatomy of the fins and tail of your betta fish!

Ventral Fins

The ventral fins are the fins positioned around the pelvic area. As a result, they’re also known as pelvic fins. They are used for swimming, turning, stopping, ascending, and descending in the water.

You’ll notice that female betta ventral fins are smaller than male betta ventral fins.

Pectoral Fins

If you have an elephant ear betta, you’re probably familiar with betta fish pectoral fins., more than most. As a betta moves throughout the water, its pectoral fins constantly move. These fins can also commonly be referred to as dumbo ears in elephant bettas as a result. 

The size and color of a betta’s pectoral fins vary according to the species, and sex.

Dorsal Fin

The dorsal fin, positioned on top of your betta fish, will vary in shape and size according to the type of betta. The primary role of the dorsal fin is to stabilize the water as your fish moves along its planned course.

Without their dorsal fin, your betta would struggle to swim straight.

Caudal Fin

The caudal or tail fin, which comes in various shapes, sizes, and colors, is also essential for water propulsion. Betta fish’s magnificent caudal fins are one of the reasons they’ve become a must-have pet for your house.

A betta fish’s anatomy is very different in the wild, but they are deliberately developed in captivity to have enormous flowing and brightly colored fins.

These lengthy fins would be ineffective in nature since they would slow down bettas, making them easy prey.

Betta fish care can be challenging if you have no idea where to start. Here’s a complete 1 page guide on how to care for them!

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The Internal Anatomy of a Betta Fish

As well as the outside of your betta, there’s also a lot of things going on in the inside too! Here are all the things that keep your betta moving!

The Esophagus

Food, water, and air are transported into the body via the esophagus attached to the Betta’s mouth. The esophagus subsequently transports these nutrients into your Betta’s body and other organs, as well as air.

Gill Arch

All betta fish have a gill arch. A gill arch is a bone support structure where both gills collaborate to convey oxygen-rich air. This air passes via the esophagus and into the labyrinth. The gill arch connects the gill rakers and gill filaments.

Labyrinth Organ

The labyrinth organ is one of the most intriguing characteristics of a betta fish. It developed over time in slow-moving, low-oxygen habitats. Thanks to the labyrinth organ, Betta fish can breath straight from the air outside their tank, instead of from the water itself.

Since bettas have a labyrinth organ, they’re classed as anabantoids. Other fish, which aren’t anabantoids, rely only on their gills to take in oxygen. 


A betta fish’s liver assists in the storage and processing of nutrients throughout the body. Food is processed in their stomach before being transferred to their intestine. To aid in the breakdown of nutrients eaten, the liver secretes enzymes known as bile.


Food is digested in your Betta’s stomach before passing through its intestine. It is then processed before being absorbed by the gut. In the stomach, vitamins, and protein, for example, are all absorbed by the intestine and utilized as fuel.


A betta fish’s kidney serves as a living filter, removing pollutants from the circulation. Betta fish can also experience kidney failure due to illnesses like dropsy.

Swim Bladder of a Betta Fish

The swim bladder is placed along the rear of your Betta’s body. It runs below the spine. It will grow in size as your betta fish matures. It appears like an elongated balloon that betta fish use to alter their buoyancy in the water.

If your Betta didn’t have a swim bladder, they’d be floating on their side or near the top of their tank.

Swim-bladder disease (SBD), which manifests these symptoms, can be caused by overfeeding and an underdeveloped swim bladder.


Male reproductive organs are the testes. These organs are exclusively found in the species’ males.


Your female will have paired ovaries instead of testes, where their eggs are produced as well as stored.

The Bladder

The bladder of a fish is the same as a bladder in us. And a betta’s kidney filters the waste that has been stored in the urine bladder.

The Anus

Waste is what remains after your fish’s food has been digested and all vitamins and nutrients have been absorbed in the stomach. The anus excretes these betta fish feces. When stringy feces hang from the anus, this would suggest constipation or overfeeding.


The heart oversees the circulating blood throughout the body. This steady pressure distributes oxygen to all your fish’s essential organs, keeping them healthy and fighting fit.

Males and Female Beta Fish Have Different and Distinctive Characteristics

Understanding the distinctions between the sexes of betta fish might help you determine if your betta fish is female or male. All keepers should understand the internal and external anatomy of betta fish. These characteristics will aid in identifying illness and figuring out what parts of the body are afflicted.

Male and female betta fish are difficult to distinguish while they are young, but as they age, male and female betta fish develop to become significantly different. Betta fish begin to demonstrate a range of sexual traits at the age of two months.

Male Betta Fish Anatomy

Males have bigger bodies and longer fins than females. In fact, they have substantially bigger tails, anal fins, and dorsal fins than females. In captivity, males will have more colorful exterior coloration on their bodies and fins too. Male bettas will also tend to have a noticeable beard.

Male betta fish will flare as he fights or tries to assert his supremacy. When the male lifts his gill covers, he exposes his beard, making him appear more noticeable and aggressive.

Female Betta Fish Anatomy

Female betta fish grow to measure just slightly smaller than male betta fish at about 2.25″. Once fully developed, however, their bodies tend to be slimmer than their male counterparts. Females also tend to have duller colorings than males.

The egg spots, also known as the ovipositor tube, are another distinguishing feature of female betta fish. A white-colored dot can be found near the ventral fins. The eggs will be discharged from this site during mating.

Frequently Asked Questions

Here are some frequently asked questions people have regarding their bettas anatomy!

Do Betta Fish Have a Brain?

Betta fish do, in fact, have brains. Just like every other living creature on earth, if they didn’t have a brain they wouldn’t be able to survive.

What Is a Betta Beard?

The opercular membrane is a membrane that lies behind the gill plate cover in Bettas. When the betta fish flares its gill plates, a membrane looks like a “beard.” Males have substantially thicker beards than females, which is typically noticeable even when the guy isn’t flaring.

Do Betta Fish Have Nostrils?

Betta fish have nares, which are effectively fish nostrils, tiny apertures in their mouths. Pheromones and amino acids are used by fish to communicate and to eat. Betta fish can smell, but they do it differently than humans.


As you can see, a betta fish’s anatomy, is complicated! But nature has found a way to keep this fantastic fish alive and thriving! If you liked this article, make sure to check out the rest of the website! Otherwise, have a great day!

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