Can Lionfish Change Gender?

About a third of lionfish have the innate ability to transition between genders. Male lionfish can become female and vice versa in many species.

You probably already knew this as a fish keeper, but some fish can physically switch genders. A wide variety of fish are capable of undergoing a sexual transition. This includes both marine and freshwater species. 

Freshwater fish, however, are more likely than marine fish to have this trait. The Atlantic Ocean, the Northern South America, and the Caribbean Sea all have warm reef areas. Hence, these are the regions where lionfish tend to thrive. 

Lionfish come in a wide variety of colors and patterns. They are fun to watch, great to have in a reef tank, and aggressive.

Why Does a Fish Change Gender?

You now know that many kinds of fishes – including lionfish – can change gender. It is natural to wonder about the reasons behind making this change. 

After reaching sexual maturity, fish switch sexes. It could be due to a loss or lack of the opposite gender.  For these reasons, fish tend to switch genders. 

Fish aren’t the only species capable of this, though. Several birds and even a few land animals also have this ability. 

When a fish wishes to change genders, its current reproductive organ starts vanishing. This continues until the organ has fully disappeared. After this, it is replaced by the organ of the opposite gender. 

So, let us assume a male lionfish wants to switch to a female. In this case, the male reproductive organ will disappear and be replaced by the female organ.   

Can Lionfish Produce Asexually?

Lionfish are incapable of producing offspring without the presence of a mate. There are both sexes, and they need to mate in order to have children.

As mentioned, some lionfish are capable of switching genders. However, this does not mean they can reproduce all on their own. 

They cannot be classified as hermaphrodites since they exhibit sexual dimorphism.

How to Distinguish Between Male and Female Lionfish?

Lionfish are a popular choice for aquarium inhabitants. This is because of their stunning beauty and unique striped patterns. 

They go by several other names, including butterfly cod, tiger fish, dragon fish, and scorpion fish. Nearly two dozen species of tropical fish with poisonous spines are classified as lionfish.

Knowing your lionfish gender is crucial. This is because you should only put one male in the tank at a time. 

Here is how you can tell male and female lionfish apart:

Territorial Behavior

Lionfish can grow to a length of anywhere from 2 inches to 18 inches. The precise length varies between species. Markings, fin length, and spine fin quantities can also vary greatly between species.

Lionfish tend to spend most of their time alone. However, when mating, they can gather in small groups. These groups can comprise one or two males, and two to eight females. 

Lionfish have a strong sense of territory. For this reason, certain male species kill other species. They would rather do this than merely drive the other species away. 

Mating Behavior

The easiest way to distinguish between the lionfish genders is during mating season. 

Males get darker and their stripes become less distinct. The female’s throat, mouth, and belly turn silvery white during this phase. This allows the female to be more easily spotted. 

The male performs a circling of the female. Once this is done, the female shakes her fins and discharges her spawns. This spawn is then fertilized by the male. 

Head Size

The male lionfish usually has a bigger head than his female counterpart. Imagine you are looking at two identical lionfish. In this case, the fish with the larger head would likely be the male. 

Researching the physical characteristics of the lionfish species that you intend to breed is essential.

It is possible to tell the gender of a fuzzy dwarf. All you need to do is measure their heads. This makes them one of the most straightforward fish species to identify.

Stripes and Fins 

Pectoral fins of male lionfish typically extend past the caudal peduncle’s midpoint. For females, pectoral fins extend just to the caudal peduncle.

Similarly, males of each species have more stripes on their pectoral fins than females do.

Take the fuzzy dwarf lionfish, for instance. Males of this species have around 6 to 10 stripes. Females, on the other hand, only have around 4 to 6. 

Make sure to conduct thorough research about your chosen species. This will help you understand more about their unique traits. 

Other Aquarium Fish Capable of Changing Genders


In certain salmon species, the male releases a milt (semen) cloud in the water. This milt surrounds the eggs as they leave the female. The chum salmon is one example of such species. 

Once released in the water, the sperm is briefly viable. 

On the other hand, other salmon species have more physical contact during spawning. The sockeye salmon is an example of such species. 

When a male salmon encounters a female, he will clean her. He does this by rubbing his snout across hers. 

To fertilize her, he jiggles his body and starts moving alongside her. This allows him to deposit sperm while on the go. 

Males may cluster around a single female until she has laid her full clutch of eggs. This cluster is usually between 2,000 and 5,000 eggs. 


One of the most well-known examples of synchronous hermaphrodites is the clownfish.

Most clownfish only mate with other clownfish because they are male first (protandrous) hermaphrodites.

So the dominant (largest) female in the group turns into a male. The second largest, meanwhile, becomes the dominant female and starts laying eggs. 

The former dominant male turns into the dominant female. It then begins to lay eggs. The submissive male then becomes prominent and fertilizes these eggs. 

This is what is meant by sequential hermaphroditism.

You can also find examples of simultaneous hermaphrodites. In these species, both the ovaries and testes operate together. 

Barnacles, snails, slugs, tremadotes (flukes), and worms are a few examples of simultaneous hermaphrodites. 

Okay, and how about fish?

Simultaneous hermaphrodites are rarely found in fish. There are only a few known cases at this time. 

Ribbon Eel

Many fishkeepers see the Ribbon Eel as the most beautiful and unusual eel species. Their distinct appearance and interesting background have made them quite popular.

Adult Ribbon Eels have the ability to transition between sexes. However, this rarely happens in aquarium settings. 

The Ribbon Eel is a common sight in the Indo-Pacific. However, that is not the case in aquarium trade. 

Generally, Ribbon Eels are yellow and black in color. The precise colors, though, can depend upon age, gender, and even mood. 

Ribbon Eels are protandric hermaphrodites, meaning that they begin life as males. However, once they reach a certain age, they turn into females. 

Ribbon Eels are quite large (can grow up to 4 feet long). For this reason, they require large aquariums. They need to be fed several times a week with live food. Examples of these foods include small fish or the ghost shrimp. 


To sum up, about a third of lionfish can change genders either way. They usually do it if there is a dearth of the opposite gender. The gender-switch usually happens after maturity.

However, lionfish are far from the only fish capable of this. A number of other fish, as well as certain birds and land animals, can change gender. 

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