How To Sex Angelfish? (Male Vs. Female Angelfish)

Determining the sex of animals or birds is fairly straightforward. However, it is quite challenging to do the same with Angelfish. 

When you’re learning how to sex angelfish, just looking between its fins is not enough. You need to have a very careful eye and some experience to be able to sex an Angelfish correctly. Fortunately, we are here to help you. 

In this guide, we will tell you the different physical and behavioral factors that can help you correctly tell the sex of Angelfish. This can be extremely helpful if you want to mate or breed Angelfish – or are simply curious to know about them.

So without further delay, let’s begin! 

How to Tell the Sex of Angelfish?

When trying to figure out the sex of an angelfish, there are a few telltale signs. But before we dive into those characteristics, it’s important that you know how difficult it is when Angelfish juveniles can’t be differentiated by gender either!

How to Tell Sex of Angelfish (Based on Appearance)

how to sex an angelfish
Photo: Vineet Bharmoria
Body Shape

The body shape of male and female Angelfish are quite similar. In fact, it can be hard to notice any difference between them if you don’t have a trained eye. Observe the body shape of various Angelfish – the female Angelfish have a sleek, angular body. The male Angelfish, however, have a large, circular body. 

That said, note that certain Angelfish species like the Flame Angelfish are sexually dichromatic; so there is no visual difference between the genders.

Head Shape

Close observation will reveal a slight difference between the head shapes of male and female Angelfish. As such, the male Angelfish have a prominent, noticeable crown or nuchal hump on their heads. However, the female Angelfish have a smooth, smaller, more rounded head with no nuchal hump. This visible difference is most prominently seen on the marble angelfish. 


The head of the female Angelfish is slightly backward and in line with the forehead angle. Also, the line from their dorsal fin to their eye is straighter than the male Angelfish. Conversely, the dorsal portion of the male angelfish is more erect and forms an almost 90-degree angle with the body.


The ventrals of the female Angelfish are typically closer to their bodies and less prominent than their male counterparts. Moreover, the body of the male Angelfish generally forms a distinct angle with the ventrals.

Another physical feature to observe is their bellies. This is easier observed when Angelfish are swimming towards you in a tank. The shape of the female Angelfish’s belly is wider and slightly more prominent than the male angelfish.

Eye/Nose Band

The eyes and noseband is far more visible when the Angelfish reach maturity. It can be fairly challenging to tell the difference between the two genders in young Angelfish. However, you may observe that the eyes of male angelfish are smaller, while the female Angelfish have more prominent, round eyes. 

The male Angelfish also develop a ridge on their nose at maturity. On the other hand, the female Angelfish have a flat nose and mouth, which is in line with their forehead shape.

Breeding Tube

One of the most common ways that people distinguish between male and female Angelfish is to observe their breeding tubes. Of course, you will have to wait till the fish reach maturity to do this, as baby Angelfish do not have descended breeding tubes. Moreover, the breeding tubes are most prominent when they are spawning, so this is the best time to observe them.

The male Angelfish have a thin, pointed breeding tube that is less prominent than the females. On the other hand, the female breeding tube is more circular and prominent. These tube-like appendages are located in between the fins.

However, they are relatively difficult to spot, so ensure that you observe the fish carefully.

You might also be interested in: How Long Do Angelfish Live?

How To Sex Angelfish (Based On Behavior)

Watch Them As They Swim Towards You

Angelfish mature at about 6 to 12 months. During this time, they will begin to pair off and spawn. This is the best time to observe the breeding tubes carefully. However, their spawning habits will also help you determine which fish are carrying eggs and which ones are fertilizing them.

However, keep in mind that same-sex Angelfish will sometimes try to spawn – although it will be unsuccessful. It is best to observe the spawning habits over a period of time to accurately sex Angelfish.

Observe Their Pairings

As we mentioned above, it isn’t very uncommon to find same-sex Angelfish attempting to mate. This may confuse some observers who are trying to determine the sex of these fish.

However, male Angelfish are typically more aggressive than their female counterparts. Although this aggression is mainly directed towards other male members, it can sometimes be directed towards females as well.

You can introduce new, mature Angelfish into your tank to try and get them to mate. However, Angelfish can be very picky when choosing a mate and may not be happy with your choice.


It is vital to note that even experienced fish keepers may sometimes have trouble determining the sex of Angelfish.

These fish species look eerily similar regardless of their gender. However, it is easier to determine their sex when they are spawning, as their breeding tubes are more prominent, and their mating behavior can be charted more easily.

As such, it is best to keep a written record that you can refer back to when trying to sex Angelfish. You can also introduce other Angelfish into the tank when they reach maturity – in an attempt to get them to mate.
Note that this attempt may not always be successful, and the fish may end up showing aggressive behavior. However, it’s worth a try!

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