Goodeidae

Goodeid fish have internal fertilisation, with males positioning themselves with a flexible part of the front anal fin, separated by a notch, which makes up the andropodium.

Embryos hatch out of the egg within the ovarian follicle, and possess trophotaeniae, ribbon-like structures that emerge from the cloaca in front of the anal fin, on the ventral surface of the juvenile.

[9] The low economic importance of Goodeid fish to Mexican fisheries and industry has led to this family being largely ignored by conservation efforts, but their small size and the dedication of a small number of aquaria hobbyists has led to a recent increase in the amount of research dedicated to the family.

Recent phylogenetic studies have put the age of this family at approximately 16.5 million years, with the majority of divergence occurring in the Miocene period.

The speciosity of this family can be attributed to historical volcanic and geological disturbance in this region, which created suitable conditions for allopatric speciation of the fish.