betta anatomy

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the sum of the parts may be greater than the whole ;) 


OK, let’s take a tour of Mr. Betta’s body:


The above is a rough map of Mr. Betta's attributes. But now let us get a more in depth look. Come closer. Cloooooser... Don't worry, he's not going to bite. Or is he? 

The mouth

Every time I look closely at a betta’s face, I think of bulldogs. Of course bettas are prettier, but still, their jaw is proportionally just as impressive. The lower jaw is powerful and will shred any live worms, mosquito larva, brine shrimp, etc… The mouth is perfectly designed and positioned to devour as well as to blow bubbles, which, as you all know by now, is two of Mr. Betta’s favorite pass times. :) Bettas are voracious and if you ever try to stick your whole arm in a 60 gal tank filled with adult bettas, you will know just what I mean. AOUTCH!!!! Those guys keep biting the inside of my arm and it hurts! Like needles. Used to make it hard for me to care for my live plants. I have nicknamed them “my little piranhas” hehehehe. The same jaws can do wonders on another betta’s fins. One of my females once SHREDDED a gorgeous DT male to the point where he had no fins left. He looked like a female!! I was told by the Animal Planet crew that proprotionally, bettas had bigger and stronger jaws than... JAWS himself. Watch out great white sharks, here comes the bettas! It's a good thing bettas are small, cause on a larger scale they would be quite a handful! The might is lined with pointy teeth that work kinda like a paper shredder: CHOMP CHOMP CHOMP. When bettas latch on to each other's fins they do not let go. Actually the fins will tear and the aggressor usually leaves the scene with a nice chunk of fin in his  mouth, which he then proceeds to promptly gobble up (remember what I said? Fighting and eating are their favorite pass times LOL).

But there is more to the mouth than meet the eyes. Beyond that intimidating row of sharp teeth, lays a warm, safe place for the fry. For the bettas will carry their young inside that same mouth formerly used to chew up their food and rivals. How such an aggressive fighter can be such a gentle parent is always a sort of amazement to me. How can a male catch his falling fry in his mouth and then gently take them back to the nest and spit them out, alive and well, without harming them? Ahhhhh... The wonders of mother nature. What's most, how come the fry don't get stuck between his teeth? I always wondered about that, until the day I caught a betta (late at night) discretely flossing ;P. Because bettas floss on a regular basis, they never get cavities. Hence you will not have to worry about ever having to take your betta to the dentist LOL. So bettas are a low maintenance pet. (I think I need a vacation)...

OK so maybe the part about flossing was not exactly true, but everything else up and until that point is. I promise :).

Wait. There is more. Let us in passing mention a few other items located near the mouth. On each side of the head, you will locate one bulging eye. The head has two sides, so (let me see if my calculations are correct) that would mean that the betta has 1+1 ab2 - cd3 + (34/56) = 2. Yes, that seems about right. Two eyes it is. The eyes are protruding and the iris is usually black, while the rest of the eye can be of different color. From snow white to jet black. Bettas can move their eyes to follow a moving object. They are also rather curious about their surroundings and will check out anything new you add to their tanks with much interest. One problem bettas have: They cannot blink. This makes courtship between the male and female especially tricky, for the male cannot blink to the female to indicate that he thinks she is HOT. Also, bettas are not very good whistlers. I think that is why they had to come up with another way to show their belle that they are crazy about her: That's where the whole flaring thing comes in.

The 'beard'

Another interest trait of Mr. Betta is the presence of a membrane under the gill plate covers. Females have a smaller version of it, but in the male it is large enough to actually kinda “stick out” when the gill plate are closed. This membrane can be of various coloration, depending on the betta color. Generally, in bettas of dark color, blues and red, the membrane will be dark. But with light colored bettas, it will often have the same color as the body (yellow, white, clear, etc…). Marbles can be interesting as the membrane can also be marbled. What use is this membrane you ask? OK, OK I’m getting there, don’t be impatient! :)

Betta_flaring_from_back_copy.gif (44682 bytes)

Above: Cool shot (from underneath the betta's belly)  of a betta gill covers opened wide and of the spread membrane as a male lunges at another male. Note that this male's membrane is actually clear with a black edge. Fear not, there was a glass partition between the two males,  which explain why the 'victim' is completely ignoring the assailant.

here you can see the same membrane, 
when it is neatly tucked under the (closed this time)
 gill covers.


The membrane is designed to make Mr. Betta look bigger, meaner and more threatening to his adversaries then he’s ever been. When a betta see another rival, the first thing he will do is open his fins and his gill plates as large as he can (also known as “FLARING“), thus displaying the membrane, like a peacock if you will. When facing his rival, Mr. Betta now looks larger than life (literally :P). He is basically using psychological warfare LOL. 

For more on aggressive behavior and flaring see Betta behavior.

If you look once again at the above photo (cool angle, you got to admit) you will clearly see the membrane but you will also see the gills of the betta. I must point this out to you because here lays one of Mr. Bettas most interesting, most useful and most fascinating attribute: The labyrinth.

The labyrinth:

For in deed the most fascinating trait of Mr. Betta is his ability to breath air from the surface, just like you and I do (or almost :) ).

It is believed that because Bettas originally came from shallow stagnant waters, which contained little oxygen, Bettas had to adapt by developing a new organ, called a “Labyrinth”, which would allow them to get the oxygen they need to survive directly from the atmosphere, above the water’s surface.

The “Labyrinth” is an accessory respiratory organ, located in the gill chamber alongside and above the normal gills. It is composed of bony plates covered by a membrane through which flows venous blood. By gaseous exchange, passing through the labyrinth organ, the oxygen content is passed immediately into the blood stream, then the used air is expelled. Because only small amounts of air can be stored into the labyrinth, bettas must make frequent trips to the surface to replenish it. This is why you will see your betta regularly going back up to the surface of his bowl to take a gulp of air.

The labyrinth allows betta to survive in oxygen deprived environments, such as small bowls, and to also survive outside of water for what seems a long period of time. Bettas are sometimes found on the floor, having jumped out of their bowl, and after lying on the carpet for quite sometime, come right back to life when returned to their water. The labyrinth also allows us, breeders, to ship bettas in small amounts of water (just enough to cover their bodies) without suffering fatalities.

Last but not least, the labyrinth has one more purpose: Unsuspecting hobbyists who get into bettas will wander in and get lost inside the labyrinth. It is said that they can never find their way out :).So they become enslaved to the bettas and usually there is little hope for them to ever get out of the hobby LOL. (I should know, I am one of them LOL)

So maybe I was pulling your leg about this labyrinth trapping betta hobbyist business, but one thing I do know for sure. The main reason bettas have taken over our lives is because they have gorgeous finnage!


When born, male and female bettas all look alike, with tiny, short fins that one cannot see with the naked eye. (see fry growth for a visual). It is only around the 8th week that some of the faster growing fry will start exhibiting a longer anal fin. An experienced breeder doesn’t need much more to be able to sex such fry with accuracy. Soon, the males will stand out because their fins, (anal, dorsal and caudal) will keep growing and become, in comparison, much longer than those of their sisters. Females fins only grow so much. They soon stop developing, leaving the female with a "short hair cut" look. On the other hand, the males fins will keep growing throughout the betta's life. If one would cut the fins, one would soon see them start to grow back. Gradually, as bettas fins get longer and heavier, the fish becomes more and more sluggish. It may be hard for them to steer and maneuver with all this excess baggage. But nature has its own way of dealing with the problem: Over activity or sometimes bacterial diseases will give Mr. Betta a quick "hair cut": The fins (which are only a few cells thick) ) will tear and fall off (also called "blowing a tail"). This will usually rejuvenate Mr. Betta and he might become once again (although now ugly) active. So I guess one cannot have it all LOL. One of the biggest problem with halfmoon bettas (who have the largest, heaviest and most majestic caudal) is that they “blow” their tails most easily :(. Meaning that the tail will literally fall apart, somewhat like a large sailboat sail in a strong wind. One day your betta is glorious, the next he looks like an old torn rag LOL. Once blown, the tail will never be the same, it will grow back, but some discoloration or unevenness will occur. Thus such bettas can no longer be entered on the show circuit. They do, however, make fine breeders and will usually be discounted so you can save money and still work with great genes. Not a bad way to go is you ask me. When spawning, the fins usually will get damaged, both in the female and male. Thus once bettas have been bred they cannot be shown either. With years of selective breeding, we were able to create a large variety of fin shapes and this too adds to the attraction bettas have on us. For more info on finnage and tail shapes see betta finnage.

OK so we talked about the mouth, head, eyes, gills, labyrinth, fins and tail of the betta. I could talk about the neck of the betta, but he doesn't have one, so so much for that LOL. What does that leaves us with? A bunch of little thingies neatly packed inside Mr. Betta's body, also known as "organs" ;).

Internal organs: 

Mr. Betta's body may measure up to 3 inches in length. However you might be surprised to know that everything is crammed in the first third (behind the head) of the body while not much is happening past that point and all the way to the peduncle. (other than the spine and swimbladder that is). 

Brain, heart, stomach, guts, liver, spleen, and all the other useful gadgets seem to lodge comfortably in the “belly” area, all well packed between the head and the beginning of the anal fin. Right there you will find Mr. Betta’s you know what, well hum, I mean you know, his anus. Females will also have an “egg spot” aka the ovipositor tube. The egg spot is a good way to identify a female and tell her apart from a young male. The egg spot is a white dot, located near the base of the ventrals. It is from this egg spot that eggs will be released by the female during spawning.

    the egg spot is very visible on this female

The other half of Mr. Betta’s body is nothing more than flesh, spine and swimbladder. The swimbladder is an interesting organ, which looks like a long clear balloon stretching along the spine. One can easily see it when looking at young fry. The organ grows and elongates as the betta grows. If the swimbladder fails to grow, to match the betta’s body size, then the betta will have what is called “swimbladder disease”, which will cause him to swim vertically or to slide on the bottom of tank on his belly. (see betta diseases ).

Well, my friends, I can’t think of anything else right this moment, so I guess that about covers it for now. I am planning on adding close up photos and possibly, more technical information for the purists :) to this page at a later date and when I do I will mention it in the latest updates section on our home page.

Meanwhile, keep surfing the site for tons more info and cool pics. Have fun!!