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Can Clownfish Change Gender? Interesting Facts You Must Know

One day my nephew asked me “Can Clownfish Change Gender?”. I was surprised by this question, luckily I knew the answer. I was surprised because not every 10 year old do not have this kind of question. He saw this in a documentary and he wanted a simple answer. I am sure you also face this question one way or another. Therefore I am here to help you. Now back to the original question Can Clownfish Change Gender?.

Yes, clownfish can change their gender. Clownfish are born as a male. But they show sequential hermaphroditism. It means all clownfish consist of both male and female reproductive organs. So Clownfish can change their gender.

Can Clownfish Change Gender

There are some reasons for dominant clown females remove from their community. These are,

  • Natural death 
  • Death because of disease
  • Predatory activity
  • Catch for the ornamental industry

How Do Clownfish Change Gender?

This is a quite fascinating story so generally, they live as groups with one female fish. Clownfish have a specific system that is mainly based on their body size. In this system, the adult female clown we mention before is at the top.

So here is the interesting part of the story. In the wild, the head female clownfish always is surrounded by males. This female is larger than male clowns. The matured male fish obtain the second place in the group (act as the second commander). This male can breed with a dominant female. The rest of the male clowns are sexually immature. After the death of the dominant female fish, these male (the second commander) mating clownfish change their gender to female. 

The other interesting thing is all clownfish have gonads. But only the leader develops female gonad. On the other hand, the next dominant clown fish developed male gonads. Then these most dominant two individuals can breed. The gonad development and growth of the rest of the fish are suppressed. Because of aggressive interactions and behaviors of dominant breeding pair. 

If the dominant female of the mating pair dies or remove, the next dominant male clownfish replace that position. Mostly mating male replace the dominant female position. Then the next dominant male can develop their male gonads and become a breeding male fish. When male transfer into the female fish, male fish testes are degraded and ovary tissues are increased. This process stimulates by the brain of fish. The fish brain regulates the hormone activity of the fish.

Tomato Clownfish

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 Can Clownfish Change From Female To Male?

Clown female fish cannot change their gender into the male. This gender transition has one way. Every clownfish born as a male, but they have reproductive organs of male and female.  

When dominant female fish disappear, the matured male can replace her and become a female fish.  But after changing their gender to female, they cannot reverse it. 

Can A Female Clownfish Change Back To A Male After Being A Female?

No. Clownfish shows hermaphroditism. It means clownfish are born as one gender and can change their gender to the opposite gender one time.

But in clownfish, gender transition happens in one direction. In the early stage of life, clownfish live and behave as a male. 

If the dominant female removes the community, the next dominant male can transit their gender to the female. The matured female fish cannot change back to a male fish.

Because in the transition period, male reproductive organs degrade. The male clownfish have testicular tissue.

During the sex reversal process, their testicular tissues decrease, and ovarian tissues increase. 

After they convert to the female fish, their internal body and brain functions are completely changed. 

How Long Does It Take a Male Clownfish To Turn Female?

Shortly after the female clownfish is removed from the community, the male’s behavioral patterns are switch. The male clown who received orders from the dominant female shows aggression and dominant behaviors to other fish.

This male fish beginning to court the smaller fish as the dominant female would do before she dies. The male clownfish brain facilitates these behavioral changes. 

The fish’s inside change because of hormonal reactions. These changes in the relative neuronal activity in the male brain transmit along the hypothalamic-pituitary-gonadal axis.

Then, the brain sends signals to change gonadal tissue and blood hormones. At the time, the male begins to change sex and they enter the transition phase.

Translating male fish eat lots of food to enhance their body size. The degeneration of the testicular tissue associates with the proliferation of the ovarian tissue

As a result of sex change progress, the gonads of transition males gradually decrease the amount of testicular tissue and increased amounts of ovarian tissue.

The gonadal sex steroid hormones, especially estrogens, are key regulators of sex change in clownfish. The males’ gonad has 55% female tissues. After 40 days, ovarian tissues reaching 87%  

40-50 days after the death of the dominant female, transition testicular tissue highly is degenerated in clown male fish.

All functional clown females mature with vitellogenic oocytes in the spawning-capable phase. After 5, 6 months, the male clownfish brain entirely change into the female clownfish.

Are All Clownfish Born Male?

Yes, clownfish born as a male, and he switches to female when circumstances allow. 

Clownfish have both male and female reproductive organs in their body. These are called gonads.

55% of female tissues are available in male fish. But in normal conditions, they live and behave as male fish. 

Female clownfish are the dominant individual of the clownfish community. Male clowns surrounded the female clownfish.

What Is The Appearance Of a Clownfish Baby?

Clownfish babies look like tiny shards of glass with big eyes. Mostly they are colorless. Clownfish larvae are 3 mm in size when they hatch. 

Further, they have tiny mouths. Thus, you should provide small food particles as a diet. Rotifers are the best fish food that you can give to clownfish babies for ten days.

Then you can provide 12 hours old baby brine shrimps to them. After 20 days, give crushed flakes or freeze-dried foods to your baby clowns.  

Clownfish takes eight days to hatch. Firstly, eggs are a pale orange color, and during the developing egg period, the color changes and turns into a reflective silver.

Clownfish have parental care for their babies. At the same time, male clownfish look after the eggs, female clownfish scanning the surrounding environment.

If any predator there, she sends a warning message to the male fish.

How Do Tou Know When Clownfish Are Mating?

Step 1

  • First, observe the behaviors of tank mates 
  • Generally, the dominant clown female attacks the mating male and nipping his fins. It is a sign of the sexual maturity of clownfish.
  • When male slender to female clown, both fish are ready to breed 

Step 2

  • Carefully look at the appearance of female clownfish.
  • If female fish is pregnant, her body’s midsection will swell, because her belly is full of eggs.

Step 3

  • Carefully observe the behavior of clownfish. 
  • If fish cleaning the rocks and digging burrows in the gravel substrate, it is a sign of pregnancy
  • When they ready to spawn, clownfish select substrate to lay their eggs 

Step 4

  • Continue to observe the appearance of both male and female clownfish.
  • If they ready to spawn, the lube-like protrusion can see on the underside of the belly of both male and female clowns.
  • This tube facilitates the spawning and fertilization process.

Step 5

  • It would be best if you keep on your eyes on the areas where clownfish clean out the aquarium debris. 
  • The mating pair will select a site to deposit their eggs. They prefer flat and protected surfaces. 
  • If female ready to lay eggs, both male and female clowns swim rapidly for hours across the surface of rocks and tank decorate objects. By close observations, you can determine whether clownfish are going to spawn or not.

Do Clownfish Eat Their Babies?

No, clownfish have parental care. Male and female clownfish protect their offspring from predators.

Generally, the male clownfish try to keep their fertilized eggs clean. Some people misunderstand the behavior of clownfish. They guess that male fish will bite their eggs. But it is wrong. 

Do Female Clownfish Eat Their Eggs?

Yes, when clownfish start spawning, some of the eggs do not fertilize properly. Female clownfish eat those unfertilized eggs and decay them.

Because if those non-fertilized eggs can spoil in the tank. It can contaminate other healthy eggs too. Thus, parent clownfish remove those eggs from the population.

Generally, this happens for the first or second batch of their breeding. Several eggs of the first and second batch are not hatched well.

But generally, clownfish do not show cannibalism. They do not eat their babies or eggs. They have parental care. Male clownfish guard eggs while female clownfish guard their territory.  

Source Clownfish Gender

Casas, L., Saborido-Rey, F., Ryu, T., Michell, C., Ravasi, T. and Irigoien, X., 2016. Sex change in clownfish: molecular insights from transcriptome analysis. Scientific reports, 6(1), pp.1-19.

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About Dr.Chamika

Hello, I'm Dr. Chamika. I am a Researcher in Water quality, Aquatic organisms, and Environmental chemistry. I am a passionate fish keeper, with10 years of experience. My mission is to help other aquarists experience the joy of fish keeping.