goodeids

Goodeids are a family of freshwater fishes in the order Cyprinodontiformes, native to the Americas, with most species occurring in central Mexico and nearby regions. The family comprises roughly 40 to 50 described species distributed across several genera, including Goodea, Ameca, Alfaro, Xenotoca, Zoogoneticus, and others. They are viviparous, with internal fertilization; embryos develop inside the female and are born as free-swimming young. In some species a placental‑like structure provides nutrition to the developing embryos.

Goodeids inhabit a variety of freshwater habitats, from springs and small streams to rivers and isolated basins. They often favor vegetation-rich or rocky microhabitats and can tolerate a range of water chemistries, though many species have relatively specific ecological requirements. Males typically have a modified anal fin used to introduce sperm into the female, while females brood the young until birth. Diet generally includes small invertebrates, algae, and plant material.

In captivity, goodeids are popular among aquarium hobbyists because several species breed readily and maintain manageable populations in home tanks. However, many goodeid species are threatened in the wild by habitat destruction, water extraction, pollution, and the introduction of non-native species. Conservation efforts combine the maintenance of captive populations with habitat protection and restoration to preserve genetic diversity.

The family is named after the American ichthyologist George Brown Goode; the genus Goodea is the type genus. Goodeid fishes have been of interest to scientists studying viviparity and evolutionary biology within Cyprinodontiformes.