[Reefland]

We have had our Black Ocellaris Clownfish for about 5 months now and we believe one of them may be changing gender. The pictures below might show enough for someone educated on Clownfish to determine; I'm not sure. As you can see in the first picture, both clowns were the same size and had light orange faces.

This picture was taken on 12-25-02:


In the next picture you can see how the clown in the top of the picture has changed from the light orange face to a very dark brown face. What you really can't see is the size difference now, the clown with the dark face is noticeably larger; about 1/2" in length and is also much "thicker".

This picture was taken on 3-2-02:


Do you think the one whose color is changing and has grown somewhat larger has turned into the female?

Regards,

[Ninong]

It is more likely that the larger one will eventually become the female. Their behavior towards each other is the most reliable indicator of gender, especially in species such as Amphiprion clarkii where there is almost no difference in size between the adult males and females; however, Ocellaris clowns do exhibit a noticeable difference in size between adult males and females.

Just keep looking for signs of dominance and submission in their behavior.

[Reefland]

And that dominance will be shown in ways such as "nipping", darting at and sometimes chasing the "male" away correct? At which point is it safe to say "This one is the female"?

Thanks again,

[stang69]

rofl

Man Scott ya scared me there for a min



Jeff

[Reefland]

I thought that title might get a laugh out of someone.

[Ninong]

Originally posted by Reefland
At which point is it safe to say "This one is the female"?

When she lays eggs.

Actually you'll know a lot sooner, but I couldn't resist. It is safe to assume that the chaser will be the female and the chasee will be the male. The future male will eventually begin to tremble in submission.

[Reefland]

We think that this is pretty cool stuff. I had 2 clowns before but they never really seemed to be a "pair" like these. We sure do like our little *guys*.

[MtnDewMan]

You will love the transition that takes place. Don't be alarmed if the female chases down the male a lot, maybe even nipping at the fins and causes a bit of damage. Eventually the male will fully be submissive and shimmer and shake at any advance the female makes, giving her the knowledge that she is da Man ... I mean da Woman ... After the ritual is complete, she will not harm him any longer. If he gets out line though, she will put him back in his place.

I went through this will my 12 year old clown pair and a very ferocious pairing of my Maroon clown pair last year. I got the maroon clowns at the same time, same size. They were best buddies. 3 weeks later she the dominant one wanted nothing to do with the other. Chased him down every single chance she got. Tore fins left and right, I mean badly. After about 3 months of this, she finally accepted him as the male and she was the female. She doubled in size in that three months and he didn't grow hardly at all. Now she is clearly the larger of the two, probably nearly 3 times his size and she doesn't beat him up at all ....

Pretty cool stuff. And by the way, that is a gorgeous pair of fish.

[Reefland]

Thanks for the compliment Chuck, they are very cute.

This is definately what is taking place, the transition I guess we'll call it. There is an obvious growth rate difference between the two like you mentioned. In fact, the smaller hasn't grown a bit while the other is growing quite rapidly.

[Ninong]

Originally posted by Reefland
This is definately what is taking place, the transition I guess we'll call it.

You could also call it "sexual determination by social aggression."

[Reefland]

Are Clownfish the only type of captive fish that go through this change or do other fish like Cardinals encounter it as well?

[Ninong]

Originally posted by Reefland
Are Clownfish the only type of captive fish that go through this change or do other fish like Cardinals encounter it as well?

Scott, why do you say "captive" fish? Are you asking about ALL of the various species that are commonly kept in home aquaria or does your question imply that "captive" fish somehow behave differently in aquaria than they do in the wild?

Maybe I'm just reading too much into your question.

Anyway, to answer your question: No, clownfish are not the only fish whose sex is determined by social interaction. Sex change is really quite common among fishes, except that it usually involves protogynous hermaphroditism where the boss is the male. Clownfish are protandrous hermaphrodites where the female is the boss. There are other significant differences as well, e.g. female clownfish can never change sex back to male whereas male anthias and wrasses (protogynous hermaphrodites) can, under certain circumstances, revert back to female.

Centropyge spp. angelfish are another good example of protogynous hermaphroditism.

P.S. -- An easy way to keep the terms straight -- if you already know which sex is topgun -- is to remember the Greek origins of both terms. Proto means first (think of the word prototype, which is from the Greek prototypos or first impression). So you know that whatever follows the Greek prefix is what comes first. Gyn obviously refers to female (it's from the Greek gune which means woman) and androus obviously refers to male (it's from the Greek aner which means man). OK, I realize that didn't help much but those are the Greek roots from which the English words android and gynecology are derived.

So if a fish has to be a male first before it can become a female, it is a protandrous hermaphrodite and if it has to be a female first before it can become a male, it is a protogynous hermaphrodite.

[Reefland]

[b]Scott, why do you say "captive" fish? Are you asking about ALL of the various species that are commonly kept in home aquaria or does your question imply that "captive" fish somehow behave differently in aquaria than they do in the wild?
[/]b

I was referring to fish that are often kept in the home aquarium.

You know I thought running your post through through the "Babble Fish" translator would help me out a bit but I was wrong.

Regards,