Golden skiffia

Golden skiffia is ovoviviparous, giving birth to live young rather than laying eggs. The right and left ovaries are merged into a single organ, in which the young are gestated. This organ is capable of enlarging as the young develop. While in the ovary, the young possess trophotaenia. Each trophotaenia has three lobes containing blood vessels, which are believed to function in nutrient and gas exchange. Newborn young lose their trophotaenia shortly after birth.[3] The gestation period is 55–60 days, with a usual brood size of 10–15 young.[5]

Golden skiffia has been declared extinct in the wild since 1996.[6] Prior to extirpation, it was found in the Rio Teuchitlán, a tributary of the Río Ameca in Jalisco state, Mexico. The area of the river inhabited by golden skiffia had a slight current, with murky water and mud, sand, and silt substrate. Golden skiffia occurred at a maximum depth of 0.5 m (1.6 ft). At the time specimens were collected, shore vegetation was dominated by Acacia and Salix, while aquatic vegetation included Pistia, Ceratophyllum, Potamogeton, and water hyacinth. The shore suffers from heavy human encroachment, and the water is polluted. In 1976, an aquarium variety of platyfish, Xiphophorus maculatus was found. This introduced species was found to outnumber Golden skiffia by a factor of 50. Golden skiffia's numbers were dramatically reduced within a year, likely due to competition from X. maculatus.[3]

Golden skiffia is likely a benthic feeder, as indicated by gut contents dominated by pennate diatoms.[3]

On 4 November 2022, a team of conservationists from Universidad Michoacana de San Nicolás de Hidalgo, Chester Zoo, and other conservation groups released approximately 1,200 golden skiffia, raised in a conservation breeding program into their native range in the Teuchitlán River.[6] The project involved restoring the degraded habitat by removing non-native species and other threats from the river's ecosystem. The release is part of the conservation project Fish Ark Mexico that successfully reintroduced the tequila splitfin into the Teuchitlán. To prepare the individual fish for their return, fish marked for release were first placed in ponds to adapt to semi-captive conditions. From there they were dewormed and marked, before being taken to mesocosms in the river itself to experience and adapt to natural conditions prior to release.[7] The released fish will be monitored for five years to assess population change, reproduction, and successful growth in their natural habitat.