Michoacán Livebearer, Poecilia scarlli
Michoacán Livebearer, Poecilia scarlli. Fish caught from coastal waters off Zihuatanejo, Guerrero, November 2023. Length: 4.5 cm (1.8 inches). Catch, photograph and Identification courtesy of Vince Golder, Santa Cruz, California.
The Michoacán Livebearer, Poecilia scarlli, is a member of the Livebearer or Poeciliidae Family, that is known in Mexico as vivíparos de Michoacán. Globally, there are forty species in the genus Poecilia, of which six are found in Mexican freshwater systems that drain into both the Atlantic and the Pacific Oceans.
The Michoacán Livebearer has an elongated slender compressed body. They are sexually dimorphic with males exhibiting vibrant shades of green, blue and yellow with patterns and the females being drab shades of olive to gray. Their head is moderately robust and flattened dorsally and mouth is small and slightly oblique that opens at the front with a projecting lower jaw and a protractile upper jaw. The anal fin is elongated in male with a well defined gonopodium. The doral fin is long and extended. The pectoral fins are placed high on the body and anterior of the pelvic fins. They are small in stature with a maximum length of 4.5 cm (1.8 inches) with the females being larger than the males. The morphometrics for this species have not been published.
Michoacán Livebearer is a benthopelagic non-migratory species that are found in shallow coastal brackish and freshwater habitats in lagoons, estuaries and slow-moving steams favoring areas with abundant vegetation. Reproduction involves internal fertilization. Each female produces broods of live young in water that is between 23°C (73°F) and 30°C (86°F) . The primarily feed on algae, small insects and detritus. In turn they are preyed upon by amphibians, birds and larger fish. They relie on camouflage and large schools for protection. They are a schooling species found in groups. The Michoacán Liverbearer has a unique reproductive strategies and behavior with the males compeate for females with playful displays of aggression among males with flasy colors and swift movements and then display themselves to females, showcasing their beautiful colors and swimming in intricate patterns. After a successful courtship, females carry the fertilized eggs internally, giving birth to live young after a gestation period of about four to six weeks.
The Michoacán Livebearer is ENDEMIC to the states of Guerrero and Michoacán of the Pacific Slope of mainland Mexico.
From a conservation perspective Michoacán Livebearer is currently considered to be Data Deficient. They are adaptable to different environments however their long-term viability is threatened by loss of habitat and polution caused by human development that has caused significant declines in the their populations. They are believed to play an important role in the aquatic ecosystem contributing to the aquatic food web and used as an indicator of the overall health of the freshwater ecosystem. The are utilized by the aquarium trade due to their stricking colors.