[Fwd: BOUNCE apisto@admin.listbox.com: Approval required:]

["Frank O'Carroll" <ocarroll@acm.org>]

Message-ID: <3B36398B.5000FA19@bewellnet.com>
Date: Sun, 24 Jun 2001 13:03:40 -0600
From: Mike & Diane Wise <apistowise@bewellnet.com>
Reply-To: apistowise@bewellnet.com
To: apisto@listbox.com
Subject: Re: sex regulation of A. nijsseni
References: <002101c0fbc9$023686a0$9294b33e@chello.no>


Arild,

According to Römer's papers on the subject, you will get more females by
lowering the temperature and raising the pH. The trick is to not raise the pH
too high or the eggs are not as viable. Römer suggests breeding A. nijsseni
at pH 5.5 and raising the fry at 26ºC (79ºF) for the first 4 - 6 weeks if you
want a 50/50 male/female ratio. One of the more interesting findings was that
sex is not determined at the moment of fertilization, but depends on the
temperature of the water in which the fry are raised for the first 6 weeks. I
hope this helps.

Mike Wise

Mike Wise

Arild Madsen wrote:

> My first batch of  A. nijsseni seems to all become male.
> Should I rise or lower the temperature to get more female's in the next
> batch.?
> At wich age is the sex determined
>
> Arild Madsen




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