Endler's livebearer

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Takes any small food: crushed flake, micro pellets, frozen baby brine shrimp, frozen daphnia, frozen cyclops, live microworms, and vinegar eels. The mouth is small, so standard-sized flake needs to be crushed. They feed primarily at the surface and in the upper water column. Algae and biofilm grazing supplements the diet in established tanks. In shrimp tanks, they'll eat shrimp food without conflict. Feed twice daily in small amounts. Overfeeding is the main risk because the fish are tiny and produce waste proportional to intake, which fouls nano tanks quickly.

Compatibility

• Same genus as the common guppy (Poecilia) and interbreeds freely with them. Housing Endler's with guppies produces hybrid offspring that lose the distinctive wild-type patterning within a generation or two. If maintaining pure N-class Endler's matters to you, keep them in a species-only tank.
• Peaceful and tiny. Males top out around 2.5 cm, females around 3.5 cm. Any fish large enough to fit them in its mouth will eat them. Stick with nano tankmates: small tetras, rasboras, shrimp, snails, and other livebearers of similar size.
• Males display constantly, chasing females and flashing color at rival males. This behavior is harmless but relentless. Females need a ratio of at least 2-3 females per male to distribute the attention. A tank of all males is also fine and avoids the exponential population growth.
• Shrimp-safe. Adults and fry coexist well with cherry shrimp and other Neocaridina. The mouths are too small to eat anything but the tiniest shrimplets.

Origin and habitat

A small livebearer from the coastal lagoons of northeastern Venezuela, on and around the Paria Peninsula, with Laguna de Patos near Cumana and the Campoma and Buena Vista lagoons toward Carupano forming the core range. Franklyn Bond first collected the fish in 1937, and John Endler rediscovered it in 1975; his fish were the ones that reached the aquarium trade and gave the species its common name. For years it was treated as a form of the common guppy before being described as Poecilia wingei in 2005 by Poeser, Kempkes, and Isbrucker. The name honours the Danish geneticist Ojvind Winge, who ran early breeding experiments on colour inheritance in guppies. The wild population is under real pressure: Laguna de Patos sits beside a municipal rubbish dump, the range is small and fragmented, and the IUCN assessed the species as Endangered in its 2024 review, naming habitat decline and interbreeding with released guppies as the main threats. The fish hybridises freely with the common guppy and the offspring are fertile, which is why aquarists who want lineage purity track their stock and keep native-traceable lines apart from guppy crosses. Males are a patchwork of metallic green, orange, black, and iridescent blue; females are a plain olive-grey and noticeably larger.

Breeding

A prolific livebearer that reproduces faster than the common guppy. Females carry young for roughly 26 to 30 days and drop broods averaging around 17 fry, ranging from about 5 to 25 depending on the female's size and age. The fry are born fully formed and free-swimming at close to 8 mm and take crushed flake and baby brine shrimp straight away. Females store sperm from a single mating and keep producing broods for months, so even a lone female from a mixed tank often delivers fry. Males mature quickly, at around five to six weeks, and in a predator-free species tank numbers climb fast enough to swamp a small setup. Keeping the population in check means separating the sexes, rehoming juveniles, or running a single small predator. Anyone breeding for pure native lineage should keep the fish away from guppies and from Endler's of unverified origin.

Common problems

Hybridisation is the headline issue for anyone who cares about lineage. Most fish sold simply as Endler's in general stores are guppy crosses, and native-traceable stock comes from specialist breeders and livebearer clubs rather than chain shops. If purity is not a concern, the care is the same either way. The other recurring problem is overpopulation: a handful of fish can become dozens within months and foul a small tank, so regular culling, sex separation, or a predator keeps things stable. The species itself is hardy and tolerates a broad range of water chemistry, and disease is uncommon in an established tank.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size