[AquaticLife] new to the group
There appear to be many factors in determining sex ratios of fry. Some of these may interact with each other. This is an area that could do with more study. Some of the factors involved may include pH, temperature, and other water quality aspects. Plain old natural selection may also be involved, such as with your guppies. The males are more colorful, even in the wild, which will make them more vulnerable to predation. More males would be produced to ensure that there are enough to ensure the continuation of the species.
\Steve//
Category: Philippines Internet Koi Society
