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Sexing Angelfish

Figuring out how to tell the sex of an angelfish is notoriously tricky. Only when you observe male and female angelfish very carefully can you tell the difference between them.

You may wonder, why is it important to know whether an angelfish is male or female?

Sexing Angelfish

Sexing angelfish can help aquarists avoid territorial disputes and aids in breeding. Below, we point out how sexing angelfish is done as accurately as possible to avoid any issues.

Behavioral Differences

When considering how to sex angelfish accurately, one way to go about it is by observing the behavior of the fish. Many aquarists know that angelfish can sometimes be aggressive towards other tank mates or even members of their species. However, what may not be immediately apparent is that it’s generally only male angelfish which are aggressive.

Angelfish are territorial fish, and this is particularly easy to see in males. Male angelfish will choose an area as their own and guard it, nipping at other males or fish of other species that come too close. On the other hand, female angelfish only tend to be aggressive when guarding their eggs or fry.

Differences in swimming behavior can also help you when it comes to sexing angelfish. Male angelfish tend to swim with their heads parallel to their tail fins. Female angelfish often swim with their heads slightly elevated. In addition, during breeding, males may spread their fins and do a bit of a shaky dance to attract females. Females will return the gesture, but it’s always male angelfish who initiate this dance.

Breeding Tubes

Most aquarium keepers agree that the most reliable angelfish sexing method is to look at the breeding tubes for male vs. female angelfish. Breeding tubes are the tubes used during reproduction from which sperm and eggs are released. Because they have different functions, the tubes in male and female angelfish are slightly different shapes.

Male angelfish breeding tubes are generally small and pointed in shape, somewhat like a cone. The breeding tubes of female angelfish are a tiny bit larger and are usually rounder in shape.

Breeding tubes are always present on angelfish, but they become more prominent during breeding – when sexing angelfish is the easiest. Luckily, angelfish swimming near a breeding pair also displays more prominent breeding tubes, so if you’re trying to determine the gender of particular fish, you can place them near a breeding pair to get a reasonably accurate idea.

In addition to assisting in telling the difference between male and female angelfish, breeding tubes can also help you determine when your fish have matured. Breeding tubes generally appear when angelfish are between six months and 12 months old and signal that the fish are ready to breed.

Enlarged Crowns

Another thing some aquarists look for when determining the difference between male and female angelfish is the head shape. Female angelfish often have flat heads with eyes and noses that are in line with their foreheads. On the other hand, male angelfish often develop a raised bump, known as an enlarged crown, on their heads, and their nose and eye area sometimes form a ridge.

These head shape differences can sometimes be challenging to spot, and they’re not always completely accurate when it comes to sexing angelfish. However, combining these features with other sex markers can help aquarium keepers more accurately tell male and female angelfish apart.

Body Shape Differences

There are also slight differences in body shape that can help when sexing angelfish. When viewed in profile, female angelfish are usually rounder than their angular male counterparts. In addition, male angelfish are often somewhat larger than female angelfish.

Angelfish Shape Differences

Angelfish males also tend to grow a bit more quickly than females and, although their shape is more angular, are somewhat rounder when it comes to girth. Pregnant angelfish, however, may also seem more significant in width, as they are full of eggs.

Fin Differences

Angelfish will often hold their fins differently depending on what sex they are. In addition, male and female angelfish fins look a little bit different.

The fins of an angelfish female are usually smooth, whereas the ventral fins of the male fish are often forked. Males will hold their ventral fins at an angle to their bodies. Females, on the other hand, hold these fins close to their bodies.

In addition to the ventral fins, females often hold their dorsal fins somewhat close to the body, angled backwards, as they swim. The dorsal fins of the female will appear to be in line with their foreheads. Males, on the other hand, swim with their dorsal fins erect.

Observe Breeding Pairs

Freshwater angelfish should be kept in groups of about six. When raised together, angelfish will naturally pair off when they reach maturity. Observing these breeding pairs can help aquarium keepers who are sexing their fish, although they will need to wait until they are mature and ready to breed.

When it comes to breeding angelfish, owners can attempt to select a male and female, but most angelfish tend to choose for themselves. For this reason, allowing a group to divide into breeding pairs is often less stressful for both the fish and the aquarium keeper. It is one of the simplest ways of accurately sexing angelfish.

Breeding angelfish pairs tend to swim together, staying near each other for some time before they begin breeding. The couple may also become territorial. They will have picked the ideal place to lay their eggs, and during this time, they will not tolerate other fish who come too close.

It is at this point that the female will begin to become rounder. This change in shape indicates that she is carrying eggs and is ready to breed. Pregnant angelfish can carry hundreds of eggs at a time. In addition, this is also when the breeding tubes of both the male and female will become more prominent.

Angelfish Parents Guarding Eggs

The female will lay her eggs in the space that she and her mate have chosen – usually along a flat surface, such as a rock or large plant leaves. The eggs are laid in careful rows.

Check out this great guide to breeding angelfish:

After the female has laid her eggs, the male will fertilize them. The male and female angelfish will then guard the eggs, keeping other fish away from them. They will also fan their fins over the eggs to provide adequate oxygen and water movement. The parents will clean the eggs and remove any that haven’t been fertilized or are otherwise contaminated.

Both the male and female fish will continue to guard and care for the baby fish until they are old enough to care for themselves.

How to tell angelfish gender can sometimes be a very tricky thing to figure out. However, when it comes to how to sex angelfish, aquarium keepers can look at a few key features, including behavior, fin appearance, head and body shape, and, for the highest accuracy, breeding tube shape, to determine which fish is male and which is female.

Do you have a question about sexing angelfish? Leave us a comment below!

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