It is known for quite a long time that the sex of fish individuals (or amphibians or reptiles) is not fixed within seconds by insemination (as in mammals or birds for instance) but by environmental factors as temperature, pH or the degree of humic substances during the first days or even weeks of their lives. The phenomenon has been widely been researched upon by specialists at universities in Germany and other countries and should be taken as well-known by science but not by hobbyists, however. I posted on this years ago in this forum. Often we have very one-sided results in the groups of offspring of Paros (f.i. 60 nagyi all males, 2 females) that are to be explained by one factor or the other. It could prove to be difficult, however, to name the decisive environmental factor in a concrete case, for mostly it is a combination of several factors.
What one should learn by this is that this is one of the important arguments for trying to imitate the natural environmental conditions for breedings as close as possible.
The
PAROSPHROMENUS PROJECT
