What is a gravid spot on yellow molly?

A gravid spot is a dark spot that appears on the belly of a female yellow molly when she is pregnant. The spot is caused by the developing embryos, which show through the skin of the belly. The gravid spot is usually located near the anal fin, and it can be seen as early as two weeks before the female gives birth.

The size and shape of the gravid spot can vary depending on the number of embryos that the female is carrying. A female who is carrying a large number of embryos may have a gravid spot that is large and round, while a female who is carrying a small number of embryos may have a gravid spot that is small and oval.

The gravid spot is a helpful way to tell if a female yellow molly is pregnant. It is also a way to estimate how far along she is in her pregnancy. The closer the gravid spot is to the anal fin, the closer the female is to giving birth.