I've heard that the way to a male's heart is through his stomach, but not that the way to a female's heart is through the guy's stomach. ;) Apparently that's the case with Gambusia affinis, however.

"Female mosquitofish prefer mates that had a steady nutritional upbringing over those that suffered a poor start in life with a restricted diet, even though the male fish are physically similar in adulthood, a new study shows."

http://www.livescience.com/17950-fema ... -attracted-fed-mates.html

This could be another point in favor of knowing where a fish came from and/or the breeder's reputation for quality fish care.

I wonder if it's a simple case of healthy growth producing a stronger adult male overall, which in turn is more attractive?