About the species
The Endler's livebearer is one of the smallest, yet most colourful, freshwater fish in the hobby - and one of the few species that scientists themselves debated for years, unsure whether it was a true species or just a guppy variant.
Origin and conservation status in the wild
The species comes from a handful of lagoons on the Paria Peninsula in north-eastern Venezuela, mainly the Laguna de Patos and Laguna Campoma area near Cumaná, where biologist John Endler rediscovered it in 1975. Its natural range is so small that the IUCN lists the species as Endangered - threats include pollution from a municipal waste dump, habitat destruction and interbreeding with released common guppies, which dilutes the gene pool of wild populations. Aquarium stock comes almost entirely from captive breeding, which makes keeping clean bloodlines all the more relevant.
Endler's livebearer vs. the common guppy
The Endler's livebearer (Poecilia wingei) and the common guppy (Poecilia reticulata) are genetically close and readily interbreed in captivity, producing fertile offspring, which is why many hobbyists long failed to tell them apart. Molecular research, published in 2009, confirmed them as separate species: the Endler's livebearer is noticeably smaller (males reach about 2.5 cm versus 3-6 cm in the common guppy), has a metallic, patterned sheen rather than the large flowing tail fins typical of fancy guppy strains, and comes from a much smaller, geographically restricted range. In the aquarium the two are best kept apart, since crossbreeding dilutes the distinguishing traits of both.
What males and females look like
Sexual dimorphism is pronounced: males are tiny (up to about 2.5 cm) but carry intense, individually variable patterns in metallic green, orange and black, and many show a doubled tail fin. Females are considerably larger (up to about 4.5 cm), round-bodied - they are almost constantly gravid - and far more plainly coloured, from pale silver to dull gold. Males develop their full colour over three to four weeks, reaching peak intensity only after around six months.
Aquarium and water
A small group is comfortable in a tank from about 40 litres upward, with some planting where fry can hide from adults. The species tolerates fairly warm water (roughly 24-28°C) and prefers neutral to somewhat alkaline conditions, pH around 7.0-8.5 - noticeably less tolerant of soft, acidic water than many other aquarium fish, so it is a poor match for soft, peat-stained setups. Regular partial water changes and stable parameters matter more than tank size alone.
Breeding
The Endler's livebearer is a livebearer and an extremely prolific one - females give birth to free-swimming fry roughly every 23 to 24 days, in broods of a few up to about 30 young. Without separating the sexes, the population grows very quickly, which is worth planning for before buying any. Adults, especially females, occasionally eat their own fry, so dense planting or a separate rearing tank improves survival.
Diet and tank mates
The species is omnivorous and undemanding, accepting standard flakes and pellets, though the diet should include a plant-based component too. It is peaceful and gets on well with other small, calm species such as dwarf corydoras or small tetras, but should not share a tank with common guppies because of the risk of crossbreeding.
Temperament
peaceful, active, sociable, curious, extremely prolific
Suitable for
beginners and fans of small, colourful tanks
Living environment
tank of at least 40 l with planting for fry to hide
Grooming
stable warm water (24-28°C), pH 7.0-8.5, regular water changes, separate sexes if needed
Pros & cons
Advantages of the species
strikingly colourful males, suits small tanks, easy to breed
Things to consider
short lifespan (2-3 years), population grows fast without separating sexes, must not be crossed with the common guppy
Notes
In the wild it is considered an Endangered species (IUCN) due to its very restricted range in Venezuela. In captivity it readily crossbreeds with the common guppy (Poecilia reticulata) into fertile but genetically mixed offspring, so the two are best kept separately. Without separating the sexes, its exceptional fecundity makes the population grow very quickly.
