Sex change in Cichlids

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James Shingler
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Sex change in Cichlids

Post by James Shingler » Fri Nov 17, 2006 8:39 pm

Does anyone have anything on this? Its common in closely related Marine fish (before you call me a nutter). I am nearly convinced (myself) it happens in uropthalmus. And maybe a couple of others I have seen. I am not brave enough to mention these unless someone has anything more solid.

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Lisachromis
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Post by Lisachromis » Fri Nov 17, 2006 9:48 pm

I'd be very wary of claiming a sex change with cichlids. Many times the fish that changed sex was female turning male.... while in fact this was a subdominant male who only needed to be away from the top male to show his true colours.

Bas Pels
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Post by Bas Pels » Sat Nov 18, 2006 4:18 am

I know it happens in Crenicara punctatus, but just as Lisa implies, I would need to see the eggs coming out of a fish, and later see that fish doing sopmething with eggs of another, without any other male, resulting in life fry, before I would say Yes.

I do have 'C' uropthalmus myself, and noting makes me think this is not just another, very beautiful, cichlid

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Post by Dan Woodland » Sat Nov 18, 2006 7:24 am

I entered a synopsis of a conservation I had with Dr. Jay Stouffer from the University of Pennsylvania a few years ago. I won’t bore you with all the details but you’ll get the point.

Dr Stouffer performed experiments with Mbuna from Lake Malawi including Melanochromis auratus. In those experiments, he isolated males and females of a species in one sex, male and female, groups to see if any would turn from one sex to the other, in short some did. To further test he placed same sexes in a tank with partial to complete dividers ranging from clear to black to see if they possessed some kind of visual or hormonal signals to change a few lucky fish into the opposite sex, preserving the species. With these dividers in place he found that every time one or two fish would jump the fence and “change sex”. This was interesting but even more interesting was the fish that turning ended up having both sets of reproductive organs. He determined that all of them had both pieces parts and changed into the sex needed at the appropriate time.

This explains why out of your group of “10 Mbuna” there is only one or two females at any one time, if you grow them from fry. If you were unlucky enough to acquire your fish after they made their decision regarding sex you were stuck with all one sex and that would not change: This means once they make the change they cannot go back.

I’m not sure if Dr. Stouffer ever published his work for the public but I’ll try to find out.

Dan

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Darrell Ullisch
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Post by Darrell Ullisch » Sat Nov 18, 2006 12:16 pm

The Crenicara is punctulatum, there are three species in the genus, but no punctata. I believe that one was found by the Z-man up in Buffalo, NY; when the male is removed/dies, the dominant female becomes male.

I've seen reports of at least two species of Cichlid going hermaphroditic, in both cases they were males that lost their females. They later laid eggs in isolation, which then surprised their owners by hatching. The more famous of these was Ginnie Eckstein's "Tootsie", a Caquetaia spectabilis. The other was an Australian report of a Red Devil male, not certain if it was a labiatus.

There have been studies on sex determination on dwarf Cichlids, they normally are set at about six weeks. However, I've heard of at least one instance where a female agassizi that had spawned lost her male, then turned male; introduced later to a new female, "he" apparently fertilized the eggs. From the circumstances described, it would only have been possible due to a sex change. I initially considered this a dubious report; I am currently inclined to consider it very possible.
There are two kinds of error: blind credulity and piecemeal criticism. Sound skepticism is the necessary condition for good discernment; but piecemeal criticism is an error. - Egyptian proverb

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