Re: livebearer sex ratios (was) Re: [GSAS-Member] Using a Python

[June Olberding <jdolb1@direcway.com>]

Hi all,

My experience was that pH infulences gender ratio in live bearers. At first
I thought it was water temp but changing that made little if any difference
but pH did.

On liverbearer side topic, today I was talking to Wildlife employee here in
AZ near Organ Pipe Cactus Monument. There is a species of pupfish in the
spring there and only one other colony of them some 50 or so miles south in
Mexico. The springs at Organ Pipe Cactus Mon. is on the southern side of the
Monument and literally meets the Mexician boarder. The Spring is now closed
to public due to trafficing from Mexico. The water tables are currently
stable here but the Mexician habitat is at serious risk from pollution. The
fear is that the species could be lost should the OPM springs habitat go
sour so the Ranger station has built a pond in Ajo AZ and has stocked it
with 200 pupfish from the springs in hopes of successfully keeping a
breeding population. It is obvious that consideralble study and effort went
into it as they imported "muck" and a little vegatation as well as water of
course from the springs. At this location, the fish "hibernate" in the mud
at bottom of pond when water temp gets low but they couldn't tell me the
temperature, just that they do. They were very "user" friendly and proud of
their efforts and let us go and look at the pond. I was privately a little
amused mixed with concern for the fish. The pond is about 200 gallons and
looks like any little "back yard pond." I thought an endangered species
would need and get a bit more palacial housing. Apparently the pupfish in
Death Valley are at also at increasing risk  due to lowering of water table
but there are, I think, several populations/different locations and there
was no mention of capative breeding plans  for them at this time.

For any of you who may be feeling a little envy for one such as myself
sitting in the sun in the desert, it has been unseasonabley  cold and has
been raining for several days so is about like sitting in Tacoma or Seattle
with cacti out side. :-)

June Olberding

on 12/7/04 2:05 PM, haika@drizzle.com at haika@drizzle.com wrote:

> Interesting! I can say that my own tap water is very soft, so I add some
> cuttlebone bits to the filter box and some crushed coral in a media bag
> as well for my guppy and Endler's tanks. I get LOTS of male Endler's!
> Sometimes I wish I'd get more females, but I've been able to farm off
> male only trios to coworkers so they don't have to worry about dealing
> with babies (+ they get all the color). This strain is one from Bob
> Holmes.
> 
> Betty Goetz
> 
> Kate wrote:
>> Lately I have been adding some harder water fish to the fishroom and
>> making up a bin with 4 tsp marine salt and a tbsp of cichlid salt from
>> The Cichlid Exchange in Portland. It's an experiment really, all my
>> guppies and endlers were coming out female so thought I would play
>> with  minerals and temp and see if I can get the ratio improved.
>> Anyone have  feedback on that? The genetics of sex determination in
>> livebearers are  really weird, it's not an XX or XY thing, it's a YY,
>> WX, WY etc weird  thing where three different combos produce females
>> and two produce  males. So what makes a swordtail a girl or a boy?
>> According to various  universities it makes a great thesis project as
>> nobody really knows...
> 
> 
> 
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