At 07:33 AM 11/5/98 +1000, you wrote:
>Dan
>
>This topic was debated at some length on this list quite some time back and
>that discussion is still available on the archives ( I think).
>
>I think that both pH and temperature both scored well as likely factors as
>well as a couple of other factors. I think that lacustrine species
>(theoretically anyway) having evolved in a more stable environment may be
>more susceptible to being influenced by these factors if they are
>significantly different to the preferred levels. e.g. G. incisus seems to
>throw more males at pH around 7 but ratios equal at 7.6.
>
>Records, if kept are fairly seldom published and most of this information is
>at best anecdotal but may still be valuable. I personally am guilty of
>failure to keep records as well as being quick to state impressions based on
>my anecdotal experience. Most hobbyists keep their fish for fun and too much
>record keeping tends to dilute the "fun factor".
>
>On the other hand many "serious" breeders, through trial and error (rather
>than accurate record keeping) have developed a set of "rules" for each
>species that "works" for them under their local water and climatic
>conditions.
>
>As to how it works Larry, all I can use as an example is the human analogy
>based on a lot of published infertility work. The chemical nature of an
>individual woman's vaginal secretions (pH is only one factor) can
>selectively influence the chances of survival of the y-chromosome containing
>sperm over those containing the x-chromosome and thus increase the chances
>of the offspring being male. I guess that such a mechanism could also be
>operating with fish too bit there are many other possibilities as well as
>many other stages along the line of development that may be significant.
>
>
>Regards,
>Bruce.
>
>Bruce Hansen, A.N.G.F.A., Advancing Australian Aquatics.
>
>Bruce Hansen, ANGFA, caring for our aquatic ecosystems.
>
>Please visit us at http://www.ozemail.com.au/~fisher/angfa.htm
>
>
>-----Original Message-----
>From: Simon, Dan <dan.simon at attws.com>
>To: 'RSG mail' <rainbowfish at pcug.org.au>
>Date: Wednesday, 4 November 1998 15:51
>Subject: [RML] pH and sex ratios
>
>
>>Exactly what pH does one need to keep a fry tank to ensure more males
>>(or females for that matter) . I've read to lower it for more males,
>>but to what extent ? Is there any sort of guidlines ?
>>
>>Dan
>>
>