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

[<haika@drizzle.com>]

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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