Re:

[jonathan <fung@is2.dal.ca>]

Thank you Mike. I have the paper by Romer and Beisenherz. Their pH
extremes 4.5 and 6.5 are still quite acidic. In those extremes, they also
only used very few clutches, which was statisitically meaningless, since
n= # of brood. Romer and Beisenherz apparently relied on work by Rubin to
say that pH has an effect. Upon reading Rubin's paper, he only used
one clutch per condition, at only two pH values. Basically, Romer and
Beisenherz showed an effect of temperature, Rubin showed a very likely
difference by pH. However, Romer and Beisenherz failed to show a
relationship between pH and sex ratio because 1) no replicates 2) acidic
pH used only. Rubin failed to show a relationship between pH and sex
ratio because 1) he only used one brood per condition 2) only two
conditions were used (intermediate values are needed to show a trend). 3)
no replicates. These papers are useful, and that they probably are right,
but they failed to show any results with scientific certainty. Therefore,
it is worthwhile to re-investigate their work, to build on what they have
done. 

Romer and Beisenherz recommended 180 days (6 months), I have three months.
I hope you are right Mike. Otherwise, I just might go with Greg's
suggestion. Thanks Greg!!! This means that I am not screwed!!! :)

Kind Regards,
Jonathan

-------------------------------------------
Jonathan Fung... Reef Geek
Dalhousie University Honours Marine Biology
Aqua Creations Inc. Assistant Manager
writer for Marine Fish Monthly 
-------------------------------------------
email: fung@is2.dal.ca


On Thu, 14 Dec 2000, Mike & Diane Wise wrote:

> Jonathan,
> 
> If you really push your fry, sexual differences can be seen within 3 months - at
> least some of the males will start to show their secondary sexual
> characteristics. At this age they should have visible testes or ovaries.
> 
> Römer & Beisenherz have shown that temperature AFTER spawning is the primary sex
> determinant in most apistos, including A. borellii.. (See my post to this list on
> 11/29 that cites reference).
> 
> Mike Wise
> 
> jonathan wrote:
> 
> > I just thought that I would keep you all updated. I'm involved in the
> > largest non-commercial Apistogramma borellii breeding project I've ever
> > seen. I've got five 25 gallons of these cranking out clutches of eggs at a
> > rate of almost one a day. I've got eight 20 gallon rearing tanks set up
> > with a clutch in each. This shall be fun. I have to get them to grow as
> > fast as possible, water changes daily with three feedings per day. If you
> > wonder why a hobbyist would dedicate so much time to this (almost a full
> > time job), it's my honours BSc thesis. Anyone have any thoughts on how
> > long it will take for these fish to reach a size that will show sexaul
> > dimorphism? Any biologists out there have any idea whether sex can be
> > determined upon dissection if they are not sexually mature? I am
> > investigating environmental sex determination by pH and temperature, (and
> > reproductive behaviour in the P generation).
> >
> > Kind regards,
> > Jonathan
> >
> > -------------------------------------------
> > Jonathan Fung... Reef Geek
> > Dalhousie University Honours Marine Biology
> > Aqua Creations Inc. Assistant Manager
> > writer for Marine Fish Monthly
> > -------------------------------------------
> > email: fung@is2.dal.ca
> >
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