Do Clownfish Mate For Life? Are Clownfish Monogamous?

Disclosure: When you purchase something through my affiliate links, I earn a small commission. As an Amazon Associate, I earn from qualifying purchases.

When I first saw my clownfish mate, I was excited. However, as time passed, I noticed that the same two clownfish tend to reproduce. The rest of the group remained behind. That immediately raised the question in my mind. Do clownfish mate for life? Can they actually present a monogamous pattern?

Yes, clownfish do mate for life. The alpha female will spend the rest of her life with the beta male, establishing a strict hierarchy with the rest of the batch. However, if the male partner no longer exists, the most dominant male following next will take its place.

As we move forward in this article, I will elaborate on this topic and explain the anemones’ role in monogamy. I will also discuss the particular case of a single clownfish, and answer whether or not you can raise one without any partners.

Also Read: Clownfish Care Guide

Do Clownfish Mate For Life?

Clownfish are monogamous, which means they technically mate for life.^[1] However, they are not like most other tank fish. Before you bring them home, there are a few things you should keep in mind.

First of all, clownfish are protandrous hermaphrodites.^[2] That means they are all born male. However, at some point, during their existence, they become female. This is part of the reason why they are monogamous. Each female will only pair with one male during its lifetime.

The fact that clownfish are monogamous always surprises people once they realize that the species lives in schools that consist of one female and various males. The female is still the largest and most dominant fish in the entire tank.

Her mate, a male, acts as the second in command. Besides the female, he is also the largest and most aggressive of the bunch. Clownfish live in strictly hierarchical societies.^[3] The fish below the female’s mate are ranked according to their size.

They are all smaller than the most dominant male. This isn’t always accidental. The female’s mate works to ensure that he enjoys the best perks the school has to offer. Not only does he get to breed with the female, but he keeps all the best food for himself. In doing so, he plays a part in making sure that the male fish below him remain small.

Smaller males in a school of clownfish will face physical opposition in their attempts to mate with the female. But you will also find that many of the males cannot produce sperm. Therefore, they are not in a position to breed in the first place.

The female is responsible for choosing her mate. She will single out the best possible breeding partner among the options available to her. The selected males are generally the largest and most aggressive of the bunch. Males can try to stand out from the competition by extending their fins, biting, and chasing the female.

This courting behavior will persist in some manner even after the female chooses the male; at the very least, the male will become more aggressive during spawning.

When a male is chosen to become a mate, the hierarchy will change. Because this beta male has moved up, everyone below him will also move up accordingly. However, these shifts are never that dramatic. The most significant, most aggressive males merely move one step up in the pecking order. The new male will grow larger in time because his new position allows him to horde all the best food.

Because there is only one female, once she chooses a male, this is the only breeding pair to be found in the tank. The male is expected to build a nest on a bare rock substrate. If you have an anemone, the nest will be positioned near the anemone.

The female will eventually flee to the nest, chased by the male. In due time, she will lay eggs ranging from a few hundred to a thousand. Once this is done, the male will take over. It will fertilize the eggs and care for them, keeping them clean by fanning them with its fins.

Any damaged or infertile eggs will be eaten. It takes roughly ten days for clownfish eggs to hatch, at which point the male clownfish’s parental role will end.

What Happens When a Clownfish Mate Dies?

Things in the tank will take an exciting turn once the female dies. At this point, the beta male will begin to increase its weight by getting the first choice of food. Eventually, it will become the new female, taking its place at the top of the hierarchy.^[4]

This will allow the largest non-breeding male to become the new beta male. This will cause the hierarchy to shift once more, with all the juvenile fish below moving one step up. Even in this situation, the new female is expected to have the final say regarding its new male partner.

The new breeding pair will spawn, producing more eggs. The female will use aggression to dominate, not only its male partner but also the juveniles below. This allows the female to not only assert its control but also to prevent other females from forming.

Once the new female dies, the beta male becomes a female. It chooses a new beta male, and this entire cycle repeats.

The Anemones’ Role in Clownfish Monogamy

This cycle in clownfish has been attributed to their relationship with the sea anemone. Anemones are creatures that look a lot like plants. However, they are very much alive, and they use poison to paralyze the other sea creatures they encounter before ultimately feeding on them.

Clownfish are unique because they actually live in anemones. No one can say for sure why anemones do not sting and then eat clownfish, though some have theorized that clownfish have some sort of immunity or defensive mechanism that protects them from the anemone’s sting.

Regardless of the explanation, clownfish and anemones have a symbiotic relationship that benefits both of them. Clownfish use anemones for shelter. The creatures keep them safe from predators, most of whom steer clear of the anemone’s toxic stingers.

They also eat the anemone’s leftovers. It has been theorized that the limited space the anemones offer encouraged clownfish to develop a breeding strategy that limits the number of spawning opportunities by ensuring that each school has just one breeding pair.

The juveniles that share an anemone with the alpha female and beta male might have seen their growth rate undergo modification over time to keep them small in size and submissive, reducing the chances of the dominant fish evicting them from the anemone.

It should be noted that, while it is relatively commonplace for a mating pair to share its anemone with other nonproductive male fish, you also find mating pairs that live alone in an anemone.

On that matter, here is an article where I discussed whether or not can clownfish live without anemones. While it is essential for survival and reproduction, there are cases when you can neglect anemones. Moreover, I mentioned there which anemones work with each type of clownfish if you choose to take your aquarium to the next level.

Can Female Clownfish Switch Partners?

Because research into the reproductive cycle of clownfish is still a little lacking, no one knows the answer for sure. It is hard to tell what would happen if you introduced a second dominant male clownfish to a tank that already had an alpha female and a beta male.

Some people have argued that the female would discard its mate if the new male were stronger, larger, and more aggressive. This is because females are wired to identify and spawn with the best possible candidate in their tank.

With clownfish, the size and dominance of a male determine his suitability. This encourages theories that a female would abandon an old mate for a better one. However, these theories are not supported by any scientific evidence. As far as anyone knows, clownfish are strictly monogamous. They only change their mates when the female dies.

How do Clownfish Change Genders?

Some people might be wondering how the clownfish’s reproductive cycle starts. Yes, when a female dies, the beta male becomes the new female, and a high-ranking juvenile takes over as the new beta male.

But how does this entire process begin? If you have a tank filled with only males, where does the female come from? The answer remains the same. All clownfish are born male, and they become female for breeding purposes later on.

If you have two males in a tank, they will fight for dominance because, as was mentioned, the species is hierarchical. The clownfish that wins will become the female, having proven its superiority.

Scientists believe that this transition in gender starts in the brain rather than the gonads. A study designed to investigate the issue placed some male fish in a tank.^[5] In some cases, it took minutes for the dominant male to emerge.

In others, it took hours. But once this happened, even though the gonads had not changed, the dominant male started acting like a female. This encouraged the researchers to look at the preoptic area of the brain, which controls gonad function.

Female fish have a larger preoptic area with twice as many neurons as their male counterparts. Once the dominant males had emerged among the subjects, the researchers studied their brains in the months that followed.

They noted that each dominant male’s preoptic area had grown to mirror a female’s preoptic tract. In other words, the dominant male’s brain had become female even though its gonads still hadn’t changed.

Anyone who studied the dominant males by looking at their brains would have called them female. Their physical behavior would have supported this conclusion.

They would have noted that the other male fish showed no interest in fighting the dominant fish despite the provocation. You see this in female clownfish. Male clownfish would never fight a female.

The researchers noted that, while the brain underwent relatively quick changes to become female, changes in the gonads were much slower. In fact, of the 17 fish they studied, only three dominant males completely transitioned into females.

The others remained in a sort of holding pattern. Their brains were clearly female, but their gonads were decidedly male. This ultimately raised even more questions regarding the control clownfish have over their sex change. Scientists couldn’t figure out why many of their subjects had failed or refused to complete the transition even after three years of observation.

Can You Keep a Single Clownfish?

Yes, it is possible to keep a single clownfish in a tank. However, that is highly not recommended. Clownfish require the intensity of groups to thrive and establish hierarchy. That is a fundamental part of the clownfish’s life with a highly beneficial value.

If you wish to keep your numbers to a minimum, perhaps raising clownfish in pairs would be the ideal choice.^[6] However, keep in mind that even then, you’ll require a relatively large tank.

You should also adjust your food and meal portions to the number of clownfish you possess. Having a single clownfish will require attention from your side.

Otherwise, you may overfeed your fish. Here is an article I wrote that covers that issue, explaining how much and often should clownfish be fed (and what kind of food is best for them).

Conclusions

Clownfish are monogamous, which means they mate for life. Typically the dominant male will turn to a female and mate with the second most prominent male in the batch.

The two will stick with each other for the rest of their lives. Putting a more noticeable beta male may change the existing order, although the data on the topic is limited.

I hope my article has answered your question on whether or not clownfish mate for life. If you have any questions, feel free to contact me in person. Either way, I wish you the best of luck in raising these magnificent, beautiful creatures.