Re: Temp vs. sex ratio

["Ed Pon" <edpon@hotmail.com>]

The effect of environmental factors on sex-ratios is not limited to apistos. 
  I've been told that West African Dwarf cichlids like Kribs can have skewed 
sex ratios as a result of ph.  Lake Tanganyikan  killifish, 
Tanganicanus-can't remember species name, sex-ratios are affected by the 
magnesium concentration in their water is the claim made by a local breeder. 
  Leopard Geckos' and either alligators' or crocodiles' sex-ratios are 
determined by the hatching temperature. Some fish when raised in twos, 
mature into one male and one female.  So, I suspect that there is a good 
possibility that there are enviromental factors that can affect the outcome 
of your dwarf pike cichlids.  Unfortunately, finding out what the triggers 
are and the critical trigger points may be a problem unless someone has the 
time and resources to set up the experiments.


>From: "Helen Burns" <helen.burns@bigwig.net>
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>Subject: Temp vs. sex ratio
>Date: Fri, 24 Sep 1999 08:24:14 +0100
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>The recent postings regarding temperature vs.sex ratios has got me 
>thinking,
>could this apply to other species.
>The reason I am interested in this particularly is that my wild pair of
>Crenicichla regani Santarem have successfully produced two broods recently.
>The first young (5th Aug) are now 2"TL and to me they all look like males
>but perhaps they are too young to sex out, I'm not sure.  The second brood
>(5th Sept) are still with the parents and if things go like they have they
>may be thinking of spawning again anytime in the following 10 days.
>As dwarf pikes share the same habitat as some species of Apistogramma it 
>may
>be that temperature can play an important factor in the sex ratio of dwarf
>pikes also.  My breeding tank is pH6.5 and the temperature was 30c.  Due to
>the unusually hot weather we have had the temperature in the tank was high
>despite the heaterstat being set at 26c.  Any advice would be welcome
>Helen.
>Scotland.
>
>
>
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