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Notho sex change

Bela Nagy wrote:

> I had a spawning group of Noth. guentheri Zanzibar TAN 97/2.
> ........all that remained home were two females. I put them 
> into a large community tank in the living room and after 
> two months, at the age of about six months, I observed that 
> one of the females began to color up!........
> Earlier the fish was a clear female with all the 
> characteristics of the Notho females, brownish-grayish body, 
> transparent fins, the characteristic form of the anal 
> fin, etc.
> Sex-change is familiar among other fishes, did somebody 
> experienced it with Nothos?

In my experience, this is not very common with Nothos. I have, however, 
had this happen a number of times with two species - N. willerti and N. 
robustus. It has always occurred when the fish were quite old and the
transformation from female to "male" has never been complete. Typically 
the fish will become very large, sometimes even larger than other males 
in the same tank, and it will develop some body and fin color 
approaching that of the male but never quite to the same extent. I have 
not observed these changed fish to show any interest in mating with 
other true females in the tank and, although I have not proved this, I 
doubt that they would be sexually viable as males. They also never 
develop a level of aggression similar to that of the true males.

Lee Harper wrote:

> I ran an experiment about a year ago.......
> ..... I had several hundred fry in a 10 gallon tank and 
> as soon as I could detect a male, I removed it. I kept 
> on removing males and more and more males kept appearing 
> even after several months....... I believe I ended up
> with less than 6 bona fide females....

I would say this is somewhat different to what Bela has experienced and 
what I have described with N. willerti and N. robustus. In our cases we 
were dealing with mature fish of at least 6 months old.
Brian R. Watters
Professor and Head
Department of Geology
University of Regina
Regina, Sask. S4S 0A2, Canada
Tel: (306) 585-4663
Fax: (306) 585-5433
E-mail: Brian.Watters at uregina_ca

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