I am asked this question a lot. Even experienced fish keepers have trouble telling the difference between male and female betta’s from time to time, especially if they are new to keeping betta fish(1). It’s not an easy task, but with practice it can be done. Here are some tips to help you sex betta fish.
Male betta fish are usually brighter in color than female betta’s(2). A male betta may have brilliant red, yellow or blue scales with different patterns of iridescence within the vivid colors. Females will exhibit some color but it is more subdued and can be duller than the male betta fish.
Male betta fish have a more narrow head shape than females. Males usually have a more pointed head while the female’s head will be wider and more rounded.
Male betta fish have a slimmer body shape than female betta’s. Males are longer and more slender, as well as taller when observed from the side view. Females will appear shorter and wider especially around the girth of their belly region.
Stripes on Body
Look at the stripes on the body of your betta fish closely. Male betta’s will have a straight, vertical stripe down the center of their bellies while female betta’s belly stripes tend to curve outward more toward the bottom of their body and often don’t meet in evenly spaced points when viewing them from above.
Male betta fish have long and extended fins. Female betta’s have shorter fins that are rounder around the edges, especially when observed from above.
Male betta fish have longer anal fins than female betta’s. The male will extend his anal fin out when flirting with a female, however it is not as pronounced as their dorsal fin which can be up to four times the length of their body! Female’s do not flare or spread their anal fins when flirting.
Male betta fish have a forked or split tail (dorsal fin). Female betta’s dorsal fin is rounded and not forked or split.
Male betta’s are more aggressive than female betta fish. When breeding, the male becomes very territorial and will be aggressive towards any other fish in your aquarium, especially another male! The female betta is usually not as aggressive, however she may become stressed when introducing a new male into her environment for breeding purposes. Betta fish are also known to be jumpers, so every aquarium should have a good tight fitting lid.
Male betta fish have a white or blue beard in front of their mouths. This is not always very easy to see, but can be observed when the male betta flares his gills and his mouth is opened at the same time.
Male betta fish usually have larger mouths than females. When observing from above, males mouths seem to extend past the eye, while females mouth does not.
Male betta fish have small white spots on the iris of their eyes. These are not always easy to see, but can be observed when looking closely enough.
Male betta fish are said to have “love handles”. These are small white lines on both sides of their body right behind the ventral, anal and dorsal fins. Females do not have these “love handles” or any other markings on their body.
Female betta fish have an egg spot on the base of their tails. The females egg spot is closer to her body than it is on the male betta fish. When the female is filled with eggs you will be able to see this “egg spot” right behind her ventral, anal and dorsal fins. Males do not have this at any time.
Male betta fish have thicker ventral fins that are flat looking while the female fin is thinner, more rounded and may appear “ruffled”.
Male betta fish will flare or spread their gills when they are flirting with each other, right before spawning. Females do not exhibit this behavior.
Male betta fish are more aggressive than females. Male’s can be very territorial and aggressive towards other male betta’s especially if they are not separated from each other quickly enough! Females tend to be less aggressive, however stress can cause a female to become agressive as well. There is no such thing as a “Calm Betta Fish”!
Bubble Nest Building
Male betta fish are known to build bubble nests, especially when they are courting a female. Females do not build bubble nests, however they may help the male blow them by fanning their fins near his while he builds it!
Some say that male betta fish are bottom feeders, because they like to hang out at the bottom of the tank or lay on objects instead of swimming around. However, this is not a definitive way to tell if your betta fish is a boy or girl. Some females will lay about as much as males, but for the most part females are more active than male betta’s. Females tend to swim around more and be very curious about their environment.
You may now have what you need to determine the sex of your betta fish. If you are wanting a male and have a female, thats ok! You can keep them together until they are ready to spawn. The female will be able to see the nest being built inside her bubble nest and she will lay her eggs there eventually. Just make sure you have a tight fitting lid on your tank! If you are wanting a female betta fish, then separate the male from the tank immediately or he may harass her until she is stressed. You can also use a divider in your tank to separate them. Females can live together if they were raised with each other, however most betta’s will fight with tank mates. Sometimes a female betta can have a “special friend” in the tank, so if you have a male and female, try to observe them over time before deciding to remove one. If they are chasing each other around all day long, then separate them!
If you have any more questions about how to determine the sex of your betta fish, please feel free to leave a comment below!