Endler's Livebearer Poecilia wingei

Quick Stats

Tank Setup

The Endler's Livebearer (Poecilia wingei) is the livebearer most of us graduate to after our first guppy tank. It is a tiny, vividly coloured fish from the coastal lagoons of north-eastern Venezuela, where it was first collected by John Endler in 1975 and again by Armando Pou in the 1980s (the original 1975 population is believed to be extinct in the wild, replaced in the hobby by the 1980s collections and subsequent captive-bred lines). Males are 3–4 cm of concentrated colour — neon green flanks, orange belly, black markings on the chest and tail, with the intensity varying by strain. Females are 5–6 cm, silver, and almost completely plain — the difference between the sexes is dramatic, more so than in guppies. A 10 gallon is the floor; a 20 gallon long is where the species shows you what it does, because the extra horizontal space lets you keep a proper breeding ratio (3 males + 6 females) without anyone getting harassed to death.

Water parameters: temperature 22–28°C, pH 6.5–8.5, hardness 5–20 dGH. That range is the same hard, alkaline band guppies thrive in — Endlers are livebearers and livebearers, as a group, want mineralised water for proper osmoregulation and fry development. Captive-bred Endlers (which is everything in shops) will live and breed at pH 7.4 and GH 12 without complaint; wild-caught stock is slightly softer-and-warmer in preference but still well within tap-water range. I run my Endler colony at 25°C, pH 7.6, GH 10 — straight tap water, no RO, no active substrate — and a colony of 9 (3M:6F) becomes 40+ within 4 months. Avoid sustained temperatures below 18°C, which suppress immunity, and above 30°C, which shorten lifespan. A small amount of aquarium salt (1 teaspoon per 5 gallons) is optional but beneficial — livebearers appreciate the mineral content and the salt suppresses ich.

Set up the tank with a dark sandy or fine gravel substrate (the colour doesn't matter much for Endlers — they show colour regardless), driftwood, and dense planting along the back and sides. Floating plants (Salvinia, frogbit, water sprite) are non-negotiable if you want fry survival — Endler fry are 5–7 mm at birth and will be eaten by their parents and each other if they have nowhere to hide. Java moss, guppy grass (Najas guadalupensis), and water sprite are the three plants I would not run an Endler tank without; they provide cover for fry, surfaces for biofilm, and break up the swimming lanes so harassed females can escape males. Filtration should be gentle — a sponge filter is ideal because no intake can suck up fry, and a hang-on-back needs a sponge pre-filter on the intake. The species classification debate is worth knowing about: Endlers were originally described as Poecilia wingei in 1963, dismissed as a junior synonym of Poecilia reticulata (the common guppy) in the 1970s, re-elevated to species status in the 1990s based on colour-pattern and behavioural differences, and the debate continues today because Endlers and guppies hybridise freely and produce fertile offspring. The current consensus is "separate species that is not yet fully reproductively isolated", which is the polite taxonomic way of saying "the speciation event is in progress and we're catching it mid-stream". Two classic colour forms show up in the hobby: the "Black Bar" Endler (a vertical black bar behind the pectoral fin, neon green body, orange tail) and the "Snake Chest" Endler (a serpentine black pattern on the chest, often with red and yellow accents). Both are descendants of the original collections; the commercial "Endler" stock in most shops is a mix of these forms plus varying degrees of guppy hybridisation.

Tank Mates

Endlers are peaceful, lively, and too small to bother anyone. Males spend their entire day displaying to females and to each other — flashing their colours, dancing side-to-side, occasionally sparring without contact — and ignore other species almost completely. Females are schooling among themselves and ignore everyone. The species is one of the safest nano fish in the hobby for a community tank, with two caveats: do not keep them with guppies (see the Diet & Feeding section for the hybridisation warning), and do not keep them with fish large enough to eat a 3 cm male.

Compatible tank mates: every common hard-water nano community fish. Endlers live happily with tetras (Ember, Neon, Cardinal, Glolight, Black Skirt), other livebearers (Platies, Mollies, Swordtails — but NOT guppies), Corydoras of every species, Otocinclus, kuhli loaches, dwarf gouramis, honey gouramis, and dwarf cichlids (Apistogramma, rams, kribensis). They are excellent dither fish for a shrimp tank — their mouths are too small for adult Cherry Shrimp, and a colony in a planted tank will out-produce any shrimplet losses. Snails are completely ignored. A single Betta can work in a 15 gallon with Endlers if the betta is mellow, but Endlers are fast and nippy enough to stress a long-finned betta — skip the betta if you are not sure. Other Endler strains (Black Bar, Snake Chest, and the various commercial hybrids) work together fine but will interbreed — if you want to keep strains pure, separate tanks are required.

Avoid: guppies (the hybridisation warning — see the Diet & Feeding section), any fish large enough to eat a 3 cm Endler (angelfish, larger gouramis, rainbowfish larger than Melanotaenia praecox, goldfish, all cichlids except dwarf Apistogramma and rams), and aggressive fin-nippers (tiger barbs, serpae tetras, silver dollars — they will shred the males' tails). The single biggest mistake new Endler keepers make is housing them with guppies in a "livebearer community tank". Within three months the Endler colony is gone — not eaten, but absorbed into the guppy gene pool via hybridisation. If you want both species, keep them in separate tanks.

Diet & Feeding

Endlers are omnivores with a strong herbivorous lean — more so than most nano fish. In the wild they eat algae, biofilm, detritus, insect larvae, and micro-crustaceans from the weedy lagoons they live in. In the aquarium they accept every common food: flakes (high-quality tropical flakes with spirulina, not the cheap stuff), micro pellets (Hikari Micro Pellets, New Life Spectrum Thera+A 0.5 mm, Fluval Bug Bites), frozen daphnia, frozen brine shrimp, frozen bloodworm (chopped — full-size bloodworm is too big for a 3 cm male), live baby brine shrimp, and algae wafers. They will graze on algae and biofilm in a mature tank — one of the underrated benefits of the species is that they help with algae control without eating your plants.

Feed small amounts twice a day. Endlers are surface-midwater feeders by habit and will chase food to the bottom, but they cannot compete with dedicated bottom feeders like corydoras — anything that hits the sand and stays there will be lost. A pinch of flake at the surface, a small pinch of micro pellet mid-water, and a small portion of frozen daphnia or BBS twice a week is the routine that gets you the best colour. The herbivorous lean matters: a pure-protein diet (frozen bloodworm only) will eventually cause digestive issues; mix in spirulina flake, algae wafers, or blanched spinach once a week. Colour responds fast to diet — a week of spirulina and BBS turns a pale shop-fresh male into a neon textbook specimen.

The hybridisation warning is the most important thing to know about Endlers and guppies. The two species — Poecilia wingei (Endler) and Poecilia reticulata (guppy) — are not yet fully reproductively isolated and will mate freely if kept together. The offspring are live, fertile, and produce viable F2 and F3 generations. This is the central reason the species-vs-subspecies debate has been running for 40 years: by the standard biological-species definition ("species are populations that cannot produce fertile offspring"), Endlers and guppies are not separate species. By the morphological and behavioural definitions, they are. The practical implication for the aquarist is simple: if you keep them together, you will have a hybrid swarm within months, and pure Endler genetics will be lost. Most commercial "Endler" stock sold in shops is already hybridised to some degree — "Endler's guppy", "Endler hybrid", "Endler mix" are all common labels for fish that are 50–90% Endler with some guppy ancestry. If you want pure Endlers (traceable to the original 1975 or 1980s wild collections), buy from a specialist breeder who can document the lineage, and never house them with guppies. The Black Bar and Snake Chest colour forms are the two most commonly preserved pure Endler lineages; if you keep these and they throw fry with elongated tails, fancy finnage, or unfamiliar colour patterns, you have a hybrid problem.

Common Health Issues

Endlers are hardy — genuinely hardy, in the same league as Cherry Shrimp and Harlequin Rasboras. The main health issues I see are ich (almost always from temperature swings during shipping), fin rot (usually from poor water quality or a fin-nipping tank mate), and "livebearer shimmy" (a stress-induced condition where the fish rocks back and forth in place, usually caused by soft acidic water — the cure is to raise the GH and pH). They are not disease-prone and a properly maintained tank will keep a colony healthy for 2–3 years — Endlers are shorter-lived than some nano fish, but they breed so prolifically that the colony outlives any individual.

Ich is treated with the standard heat-and-salt or formalin/malachite protocol. Endlers are fully scaled, tolerate salt well (1 tablespoon per 5 gallons for 14 days is the textbook treatment, raising temperature to 28°C — do not exceed 30°C), and tolerate formalin-based medications (Rid-Ich, Kordon Rid-Ich Plus) at the label dose. The salt treatment is particularly appropriate for Endlers because they like the mineral content anyway. Copper-based treatments are not toxic to Endlers but should still be avoided in a community tank — if you have shrimp or snails, copper kills them. Fin rot responds to clean water (daily 30% water changes for a week) plus a broad-spectrum antibiotic (Maracyn, Kanaplex) in a hospital tank. The underlying cause is almost always poor water quality — fix the water and the fin regrows in 2–3 weeks.

Prevention is straightforward: weekly 25–30% water changes with dechlorinated, temperature-matched water (a small amount of aquarium salt is optional but beneficial — 1 teaspoon per 5 gallons); no ammonia, no nitrite, nitrate below 30 ppm; stable temperature; and a mature, cycled tank. Endlers are livebearers and produce a noticeable bioload for their size, especially a breeding colony — the 30 ppm nitrate ceiling is realistic, not aspirational. Lifespan in good conditions is 2–3 years — shorter than harlequins (5–8 years) or pencilfish (3–5 years) but offset by the fact that a single female produces 15–30 fry every 4 weeks. If your Endlers are dying within the first 6 months, look at water quality and the GH/pH first — the species is robust in hard alkaline water but does poorly in soft acidic water, and "livebearer shimmy" is the symptom that tells you the parameters are wrong.

Breeding

Endlers are livebearers — the female gives birth to free-swimming fry rather than laying eggs. They are among the easiest aquatic animals to breed; in a 10 gallon with both sexes present and a healthy population of Java moss, fry will appear within 4–6 weeks without any intervention from you. The male courts the female by displaying alongside her, flashing his colours, and dancing side-to-side; if the female is receptive, the male transfers sperm via the gonopodium (a modified anal fin that functions as an intromittent organ). Females can store sperm from a single mating for 4–6 months and produce multiple broods from that one mating — which is why a "female-only" tank will still produce fry for months after the male is removed.

Gestation is 24–28 days at 25°C. A typical brood is 15–30 fry, smaller than a guppy brood (30–50) because Endlers are smaller fish. The fry are 5–7 mm at birth, free-swimming immediately, and self-sufficient from day one — they will graze on infusoria and biofilm in a mature tank, or take powdered flake and live baby brine shrimp from day one. There is no parental care; the parents will eat the fry given the chance. Dense planting (Java moss, guppy grass, water sprite, floating plants) is the single biggest determinant of fry survival in a community tank — without cover, fry survival is 0–5%; with a thick moss carpet and floating cover, fry survival is 30–60%.

Sexing is straightforward at 4–6 weeks: males develop the gonopodium (the modified anal fin), start showing colour, and stay small; females stay plain silver, grow larger, and develop the gravid spot (a dark triangular patch on the rear of the abdomen where the developing fry are visible through the body wall). A single male and three females in a 10 gallon with dense planting will produce 50–100 fry per month indefinitely. The fry grow fast on BBS and crushed flake — 1 cm at 4 weeks, sexable at 6 weeks, sexually mature at 3 months. Excess fry can be given away, sold to local fish stores (most stores take them as trade credit), or used as feeder fish for puffers and other small predators. Strain purity matters: if you want to preserve the Black Bar or Snake Chest pattern, keep the strains in separate tanks — the colour forms will interbreed and produce intermediate patterns that are not as visually striking as either parent. If you are breeding for fun rather than for purity, a mixed-tank colony will throw a wider range of colour patterns and is more interesting to watch — just do not sell the offspring as "pure Endlers" if you have crossed strains.

Frequently Asked Questions