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Myths about sexing bettas

17K views 66 replies 27 participants last post by  LittleBettaFish 
#1 ·
Myths about sexing bettas
When you have a tank full of juvenile bettas, sexing them can be quite tricky as a new breeder. I thought it might be helpful to other breeders to share some of the things I have learned about this tedious task. There are 2 main myths I would like to clear up.

Myth# 1
If the betta fish has what appears to be an egg spot, the fish is female.

Fact: Although this can sometimes be true, there are exceptions.
I have seen young bettas that have what appear to be egg spots at a few months of age that turn out to be males. The "egg spot" mysteriously disappears as the fish grows longer fins. Things are not always as they appear.
This picture is a good example of a young male that seems to show an egg spot.


This is the same fish about a month later.



Myth #2
If the betta fish shows vertical bars, the fish is female.

Fact: Immature male bettas will often show vertical bars while in a group of bettas. Vertical stripes is how bettas show submission, and even an adult
male may show vertical stripes. When a male betta shows these stripes, it seems to communicate that he is submissive to the other fish. Perhaps
he is scared, stressed or wants to avoid a fight.

Here is a juvenile betta showing vertical bars that later developed into a male.


The only sure way to tell apart females from male bettas is to hold the fish up to a very bright light and look for ovaries. The body shape is often shorter and curvier on female bettas, but well fed juvenile fish can all look curvy. The anal fin and ventral fins of male bettas is usually more pointed
and longer. Female plakats may appear to be male if you go by fin shape. Unless you can see ovaries when held up to the light, the fish might not be female.
 
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#3 ·
This is kinda off topic but I didn't know a betta's colors change so dramatically as they grow. Great info though! I'm not a breeder but this stuff is so interesting to me.
 
#4 ·
Don't expect aggression to be a tell tale symptom either. I have a dominant female in my fry tank who flares all the time but she is most definitely a female (light bodied so the ovaries are clearly visible).
 
#8 ·
My boy has an egg spot. Super confusing when I first got him, because in every other way he is definitely male. I was worried there was some wierd hormonal thing going on. :-? It's a relief to know that other males have an egg spot. I think this should be stickied too!
 
#9 ·
I vote to sticky this! Everything she posted is 100% true.
 
#12 ·
i agree its very true and should be noted for everyone to see.

But isn't it also true that bettas can change gender if not sexed between the months of 5-10 months old?
 
#14 · (Edited)
1fish2fish,

I respectfully disagree. :)

Given the right conditions, female bettas are capable of changing to male. Of course it does not happen suddenly. According to my source, if a female has spawned, she will always be female. Of course there are some males that are just slow developers, or maybe not? Anyway, I personally have seen cellophane fish with very visible ovaries that matured later into fully functioning males. I thought I was going crazy until I asked someone at a show who would know more than me about bettas changing sex. Many types of fish are capable of changing their gender. It is not unusual at all for fish. For example clownfish can change from male to female and Centropyge angelfish can change from female to male. Anyway, yes female bettas may be capable of changing to male just like many other types fish.
 
#18 ·
IMO they can't change gender. I have a male that even the experts said was female and guess what...he's a daddy! I think these cases are just mistaken identity of the fish...still interesting though.
 
#19 ·
Although it has not been officially documented with bettas, many types of fish in general are capable of changing their gender naturally. This is a proven fact. I'm not really 100% sure if bettas can change their gender, but Leo Buss told me that he thinks they can change from female to male. I respect his opinion.:)
 
#22 ·
I dont know if it is true for bettas.. but dragon lady is correct that many fish do this. Grouper change gender and so do swordtails. I believe it is generally females changing to male. I've read that they do this if there are not enough males in their living space. I have personally seen one of my female swordtails change.
 
#23 ·
I agree... I don't believe bettas are hermaphrodites or capable of changing their sexes. I know most fish are, though. I have paired different clown fish to one another and one of them (usually the smaller one) turns into a male.

Great info on determining the sex but would you please explain or show photos of a betta in the light with ovaries showing?
 
#24 ·
Great info on determining the sex but would you please explain or show photos of a betta in the light with ovaries showing?
I would like to see this as well.
 
#25 ·
Although I can see in real life on darker bodied females when held up to a bright light, it is easier to photograph on lighter bodied females. The best comparison I can think of is looking at a baby chick through an egg shell under a bright light to check for female organs. I hope this helps explain how to identify a female betta a bit better. :)

Anyway, here are several photo examples of where to look to see if you have a female betta.




The female parts are located where she bars up.







By the way, here is an article that proves that female bettas are capable of sex reversal.

Sex reversal in female Betta splendens as a function of testosterone manipulation and social influence
Abstract

In Experiment 1, female Betta given daily injections of testosterone (T) for 9 weeks acquired anatomical features characteristic of males as indicated by changes in fin length, body coloration, and gonadal morphology. These findings suggested that a potential for sex reversal exists in females of this species. In Experiment 2 we measured changes in aggressive behavior during testosterone-induced anatomical changes. Aggression decreased toward females and increased toward males as treatment with T progressed. The final displays of aggressive behavior and anatomical characteristics of fish injected with T resembled those of typical males. In Experiment 3, female Betta primed with T injections for 3 or 6 weeks and permitted to interact socially with females continued to display characteristics of sex reversal after T supplementation ceased. Sex reversal in isolated fish injected with T for 3 or 6 weeks was not sustained, and fish receiving only the control vehicle showed negligible change in both the isolated and community conditions. We discuss the results in terms of similarities with the sex change process found in isolated communities of coral reef fish.

Source:
http://www.ncbi.nlm.nih.gov/pubmed/3180734
 
#28 ·
From my understanding-this is artificial sex reversal and not natural sex reversal, however, I have seen natural sex reversal is some species of saltwater species.....I have not been able to find any information on natural sex reversal in the Betta splendens only artificial in scientific research

Got any scientific study links for natural sex reversal....this is a very interesting subject.....

Here is a link about sex reversal in dogs....http://onlinelibrary.wiley.com/doi/10.1002/mrd.1080390102/abstract

I wish you didn't have to buy some of the studies they have on that site...some would really be interesting to read
 
#30 ·
baylee767,

Now I'm wondering if the bettas bought retail are all sexed CORRECTLY. O_O

Your average consumer: a) wouldn't know the difference; b) would only put one betta per container; and c) isn't going to try to build a sorority.

Argh.
 
#32 ·
I've been able to successfully tell gender by the shape of the face...males have thicker gill plates and tighter jaws.
 
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