Endler Guppy Details
Endler Guppy Details
Wild Status, Grading, Genetics & Pure Strain Documentation
Wild Status, Grading, Genetics & Pure Strain Documentation
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Species Profile Overview
Species Profile Overview
An in-depth guide to Endlers Libebearers (Poecilia wingei) genetics, coloration and pattern grading, Pure Strain N Class documentation, natural history and conservation status — tailored for advanced seasoned hobbyists and enthusiastic fans. You’ll find clear, reliable guidance to help you understand what makes Endlers unique and how to identify, appreciate, and care for them with confidence.
Conservation Status in the Wild
Conservation Status in the Wild
As of 2021, Endlers’ livebearer (Poecilia wingei) are officially listed as Endangered (EN) on the IUCN Red List of Threatened Species due to severe threats to its native habitat and hybridization with released guppies in northeastern Venezuela. Their range is restricted to coastal lagoons and streams on the Paria Peninsula and surrounding areas, making the species particularly vulnerable to environmental change. Wild populations face ongoing threats including habitat loss and degradation, pollution, invasive species, and hybridization with released guppies (Poecilia reticulata), all of which jeopardize their long-term survival in nature. DNA Testing of wild populations in Venezuela has confirmed the occurrences of hybridization with common guppies.
Why this matters: N Class Pure Strain Endlers preserve the last documented, genetically verified link to wild Poecilia wingei, protecting their original coloration, behavior, and genetic integrity. Choosing documented Pure Strain N Class Endlers supports genetic conservation, authenticity, and stable, predictable breeding outcomes for future generations.
Grade: B / Class: N (Pure Strain) / Strain: Black Bar
Endler Grading Overview
Endler Grading Overview
Grade refers to how closely an individual fish matches an ideal or prime specimen for its specific strain.
Grade A males represent Best-in-Breed specimens.
Grade B/C males display more common traits and standard-to-symmetrical patterning of the strain.
Detailed grading standards are listed within each Strain section below. The images on this page provide visual examples of Grade, along with Class and Strain.
The Endler Shop developed these grading standards during selection of Best-in-Breed males used to produce future generations. Grade A males exemplify the closest match to a “perfect” specimen, distinguished by exceptional coloration, precise strain patterning, strong finnage, superior symmetry and balance, and optimal size. Every Endler has its own distinct beauty, but contrasted with a Best-in-Breed Grade A male, and the difference in quality, color, and presence is unmistakable.
Important note: Grade A males possess a majority of the key characteristics, which qualifies them for A-grade status, but may not display every ideal trait.
Grade: C / Class: N (Pure Strain) / Strain: Black Bar
Black Bar Strain Grading
Black Bar Strain Grading
Black Bar Endlers — Strain Overview
Black Bar Endlers — Strain Overview
Black Bar Endlers are defined by a bold, black bar on each flank, creating dramatic contrast against the fish’s adjacent vibrant body coloration. In addition to the signature black bars, body colors commonly include red, orange, and yellow, with occasional hints of green. Fine speckling of blue, green, or purple may occasionally also be present.
A light blue patch beneath the dorsal fin is often visible, while the tail typically features a red or orange “sword-and-a-half” pattern outlined in black. The dorsal fin may be clear, or display orange, red, or black coloration.
Black Bar Endler Grading Standards
Black Bar Endler Grading Standards
Grade A — Best in Breed
Grade A — Best in Breed
Black bars are deep, solid black, thick, and smoothly curved
Bars extend from beneath the eye to just under the dorsal fin
Bars are unbroken and relatively symmetrical on both sides of the fish
Dorsal fin shows visible coloration (not clear)
Tail has a thick black outline along most of the top and bottom
Adjacent to the tail outline is a red/orange band, often with whitish-blue tips
Generally largest of the Grades
Grade B — Symmetrical
Grade B — Symmetrical
Black bars may be less intensely black and are thinner and smaller than Grade A
Bars usually do not extend fully from eye to dorsal fin
Bars often remain unbroken and symmetrical on both flanks
Dorsal fin occasionally shows some coloration
Tail has a thin black outline along part of the top and bottom
Adjacent to the tail outline is usually red or orange, sometimes with light blue tips
Generally smaller than Grade A
Grade C — Standard
Grade C — Standard
Black bars are smaller, thinner, and often less dark
Bars usually do not extend fully from eye to dorsal fin
Bars are often broken, globular, or asymmetrical
Dorsal fin is usually clear
Tail shows some color, but typically lacks a black outline
Tail color is often clustered near the base of the tail and does not reach the tips
Generally smallest of the Grades
Grade: A / Class: N (Pure Strain) / Strain: Black Bar
Peacock Strain Grading
Peacock Strain Grading
Peacock Endlers — Strain Overview
Peacock Endlers — Strain Overview
Peacock Endlers are distinguished by a bold, black “peacock” spot on the tail, which serves as a striking focal point and contrasts sharply with the fish’s bright body coloration. Along the upper portion of both flanks, a red or orange stripe, sometimes broken, runs horizontally, with one or more black spots positioned below the stripe. Additional body coloration commonly include swirls of yellow and green, with rare speckling of blue, green, or purple. The tail typically displays a red or orange “sword” on the top, bottom, or both, often outlined in black. The dorsal fin may be clear or may show orange, red, or black coloration.
Peacock Endler Grading Standards
Peacock Endler Grading Standards
Grade A — Best in Breed
Grade A — Best in Breed
Tail features a large, bold, deep-black peacock spot
Body shows at least one large, round or oblong deep-black peacock spot
Upper flanks displays a bright orange stripe, usually unbroken
Tail shows thick, saturated coloration along both the top and bottom
Dorsal fin usually displays color
Both sides of the fish are relatively symmetrical
Generally largest of the Grades
Grade B — Symmetrical
Grade B — Symmetrical
Tail displays a medium-sized black peacock spot
Body has at least one medium-sized black peacock spot
Upper flanks shows an orange stripe, which may be broken
Tail displays some coloration along the top or bottom
Dorsal fin has little or no color
Both sides are somewhat symmetrical
Generally smaller than Grade A
Grade C — Standard
Grade C — Standard
Tail has a small or lightly colored black peacock spot
Body shows small or faint black peacock spot(s)
Upper flanks have a light orange stripe, usually broken
Tail displays minimal coloration
Dorsal fin is typically clear
Both sides are often asymmetrical
Generally smallest of the Grades
Grade: A / Class: N (Pure Strain) / Strain: Peacock
Genetics Explained
Genetics Explained
Genetics play a huge role in what makes Endlers so special. From color and pattern to size and breeding outcomes, understanding the basics of Endler genetics helps hobbyists make better choices and avoid surprises.
One of the most fascinating aspects of Endler genetics is how male coloration and patterning are inherited. In most cases, the vibrant colors and distinctive markings seen in male Endlers are passed down through the Y (male) chromosome. As a result, male offspring tend to closely resemble their fathers, often producing strikingly consistent traits from generation to generation. As with all biological systems, inheritance is complex, and exceptions do occur. For a deeper dive into this topic, see this Endler / Guppy Genetics Primer.
Additional Endler Genetic Facts
Endlers have 23 pairs of chromosomes, including one pair of X and Y sex chromosomes (the same number as humans).
Endlers can hybridize with the common guppy (Poecilia reticulata), producing fertile offspring.
They have been crossed with picta livebearers (Poecilia picta), resulting in offspring with varying fertility.
Crosses with certain molly species (Poecilia latipinna and Poecilia velifera) reportedly produce all-male offspring that appear to be infertile.
Grade: B / Class: N (Pure Strain) / Strain: Peacock
Poecilia wingei Species Recognition
Poecilia wingei Species Recognition
While the taxonomic status of Endler’s livebearer was debated for years, scientific consensus solidified with its formal designation as Poecilia wingei in 2005. This classification established it as a species distinct from the common guppy (P. reticulata) following rigorous morphological and genetic analyses.
Evolutionary Origins
The exact timeline of divergence remains a subject of ongoing research. While some estimates suggest Endlers diverged from guppies hundreds of thousands to a few million years ago, precise dating varies by methodology and is not yet fully resolved. However, it is established that P. wingei evolved independently within the isolated coastal lagoon systems of northeastern Venezuela. This specific environment shaped the unique traits that define the species today.
Overcoming the Hybridization Debate
A primary challenge in defining these species boundaries is that P. wingei and P. reticulata can interbreed and produce fertile offspring. Despite this potential for hybridization, the conclusion that P. wingei is a valid, distinct species—rather than a subspecies—is supported by a growing body of evidence:
Distinct Morphology: Unique anatomical features and reproductive anatomy distinguish Endlers from other livebearers.
Molecular Phylogeny: Studies of mitochondrial DNA sequences show that P. wingei forms a separate taxon from both P. reticulata and the related P. obscura.
Behavioral Divergence: Distinct evolutionary trajectories are evidenced by significant differences in mating behaviors and color pattern structures in wild males.
Key Evidence for Taxonomic Separation
Modern science utilizes several layers of evidence to support the distinction of P. wingei:
Study Year / Key Findings / Researchers
2005 Formal species description of P. wingei./ Poeser, Kempkes, & Isbrücke
2009 Used mitochondrial DNA (D-loop and cytochrome b) to confirm P. wingei as a separate taxon / Schories, Meyer, & Schartl
2010 Combined nuclear and mitochondrial DNA to further validate the species distinction / Meredith et al.
2018–2022 Various Genomic Studies Confirmed that while they are "sister species" sharing an ancestral sex chromosome, they possess species-specific Y-chromosome patterns.
Summary of Diagnostic Traits
Despite a 2014 paper that questioned previous findings, the prevailing scientific view recognizes P. wingei as a distinct species based on four pillars of research:
Consistent anatomical differences in body structure and fin shape.
Unique color pattern structures found in wild-type males.
Geographic isolation in the unique ecosystems of northeastern Venezuela.
Molecular genetic separation that consistently differentiates their lineage from P. reticulata.
Grade: C / Class: N (Pure Strain) / Strain: Peacock
N Class Pure Strain vs P Class Endlers
N Class Pure Strain vs P Class Endlers
N Class and P Class Endlers may look similar at first glance, but meaningful differences emerge in genetics, coloration, behavior, and body structure.
While P Class fish are typically identified by documentation alone, real-world observation often reveals subtle signs of past hybridization when compared to true N Class Pure Strain Endlers. This section explains how these two classes differ, what those differences look like in the aquarium, and why genetic purity matters, helping hobbyists understand, identify, and choose Endlers with confidence.
What Sets N Class and P Classes Apart
What Sets N Class and P Classes Apart
By definition, the difference between N Class Pure Strain and P Class (Undocumented Lineage) Endlers should be limited to documentation, specifically, verified proof that the fish have not been crossbred with common guppies. In theory, the fish themselves should appear essentially the same.
In practice, however, that has rarely been my experience.
Nearly every time I’ve encountered fish P Class Endlers, I’ve observed signs suggesting some degree of past hybridization. When compared side-by-side with N Class Pure Strain Endlers, consistent differences emerge in behavior, color intensity, color pattern complexity, number of colors expressed, and overall body shape and morphology.
At a casual glance, N Class and P Class fish can look quite similar. But after years of observation, I believe that the vast majority of P Class Endlers found in the hobby today, including those commonly sold in pet stores, show at least some level of guppy hybridization.
Below are the specific differences I’ve consistently observed.
N Class Pure Strain Males
Slightly smaller and more streamlined in body shape
Display a broader range of colors and patterns with noticeably deeper saturation
Colors exhibit a strong metallic or iridescent “neon” sheen that is difficult to capture in photographs, more like glossy paint than flat
Dorsal fins tend to be smaller
Tails remain natural in shape, without exaggerated forms common in modern guppies; tail “swords,” when present, are not excessively elongated
Interact with one another in more structured and coordinated ways, occasionally swimming in loose synchrony
N Class Pure Strain Females
Slightly smaller and more streamlined
Less likely to prey on fry
Show greater interest and engagement during courtship behavior
When I first transitioned from keeping P Class fish to N Class Pure Strain Endlers, my immediate impression was: “These fish seem wild.” There was a distinct presence and intensity that I couldn’t immediately articulate, but it was unmistakable.
In hindsight, that impression clearly stemmed from the combined physical and behavioral differences outlined above. A useful analogy is the contrast between wolves and domesticated dogs. P Class Endlers appear to have developed slightly “softer” traits, both physically and behaviorally, while N Class Pure Strain Endlers retain a more wild, ancestral character.
Maintaining the genetic purity of N Class Endlers is essential for long-term conservation and preservation of their original traits. That said, P Class Endlers are appealing in their own right. In fact, some of their more “dog-like” qualities” can make them especially enjoyable aquarium fish.
Both classes have their place in the hobby. Understanding the differences allows hobbyists to make informed, intentional choices.
Grade: C / Class: P (Not Pure Strain) / Strain: Peacock
Pure Strain N Class Documentation
Pure Strain N Class Documentation
Origins of N Class Pure Strain Endlers
Origins of N Class Pure Strain Endlers
Very few, if any, direct descendants of the Endlers originally collected by Dr. John Endler in 1975 remain today. Over time, widespread hybridization and inbreeding diluted those early lines. However, after direct consultation with Dr. Endler, a wild fish collector later undertook new expeditions to Venezuela to locate and collect Endlers from their native coastal lagoons.
Beginning in the late 1990s and continuing into the following decade, these expeditions successfully gathered hundreds of wild Endlers directly from their natural habitat. This fresh wild stock became the foundation for expanding and stabilizing captive Pure Strain breeding populations.
Pure Strain Endlers (Poecilia wingei) are formally listed on the IUCN Red List of Threatened Species as Endangered in the wild due to habitat loss, pollution, hybridization with the common guppy and other threats to their limited native range in Venezuela.
The reality is that the pure Endler is vanishing in their native environment. Due to human-led habitat changes, common guppies have flooded Endler lagoons, leading to hybridization. Because it's no longer clear if newer wild-caught fish are free from guppy DNA, we rely exclusively on documented lineages that predate this environmental shift and those resulting consequences.
In hindsight, the importance of these collections cannot be overstated—without them, Endlers as a distinct genetic lineage may not exist at all today. This foundational stock was entrusted to the Endler Livebearers Association of America (ELAA) to ensure its preservation and responsible distribution.
N Class Pure Strain Endlers: Lineage Verification Explained
N Class Pure Strain Endlers: Lineage Verification Explained
Only fish that are direct descendants of the original ELAA stock and whose lineage is fully documented across every generation are recognized as N Class Pure Strain Endlers. This verification is maintained through official breeder registries. The Endler Shop is listed in the ELAA N Class Pure Strain Registry (under my name as a breeder), documenting our Endlers directly back to the original wild-collected stock. See the ELAA Registry screen captures on this page, highlighted in yellow. Our ELAA Registry listing formally validates our Endlers as authentic N Class Pure Strain fish.
The Endler Shop's Documentation of Customer N Class Fish
The Endler Shop's Documentation of Customer N Class Fish
The Endler Shop extends this same level of documentation to our customers. We maintain our own N Class Pure Strain Customer Registry, which records eligible purchases and completes the lineage trail—from the original ELAA stock, through our breeding program, and finally to the customer.
Customers who purchase qualifying N Class Endler orders (typically 8 fish of a single strain, mixed males and females) may request inclusion in The Endler Shop's N Class Pure Strain Registry at the time of purchase. Once registered, this documentation verifies the full pedigree of their fish as true N Class Pure Strain Endlers, preserving both genetic integrity and historical continuity.
View current available registered N Class Pure Strain Endlers in the Shop.
A very deep dive: Endler History
A very deep dive: Endler History
The History, Preservation & Documentation of Endlers Livebearers
1970s — Scientific Discovery & Early Introduction
In 1975 evolutionary biologist Dr. John A. Endler rediscovered wild Endler populations in northeastern Venezuela, particularly around Laguna de los Patos near Cumaná. The species had been first collected from the same region by Franklyn F. Bond in 1937, but that early collection was not published or widely recognized until Dr Endler’s work brought it to scientific and hobbyist attention. Very few, if any, direct descendants of Dr. Endler’s original 1975 collection remain today due to widespread hybridization with common guppies and genetic bottlenecks diluting those early fish.
Late 1990s to Early 2000s — Wild Collections & Foundation
In the late 1990s and early 2000s, Armando Pou (urged by Dr. Endler) collected and documented wild Endlers from distinct locations in northeastern Venezuela. These collections form the genetic foundation of many modern Pure Strain N Class preservation lines. Key Collection Sites:
Cumaná Region: Laguna de los Patos (North and South lakes), Laguna La Malagueña, Black Endler Pond (near Autopista Sucre), Hyacinth Stream
Campoma Region: Laguna Campoma and surrounding streams, Bridge collections, El Tigre Stream
Cariaco area: Laguna Buena Vista
Many original lines like Black Bar and Peacock Endlers (which we maintain at The Endler Shop) trace directly to Armando Pou’s collections in 1997, 1998, and 2004 (both strains collected in each of those years)
Black Bar: from the Cumaná lake systems including Laguna de los Patos North & South lakes and connected lakes
Peacock: from the Cumaná region, including both Laguna de los Patos North Lake and Laguna La Malagueña
The Foundational Advantage: Because these early field collections occurred prior to intensified habitat disruption and widespread feral guppy introduction in Venezuela, they represent a significantly lower risk of hybridization compared to undocumented modern collections.
DNA Testing of wild populations in Venezuela has found that as geographic barriers (like lagoons being connected to the sea or to adjacent rivers through human activity) disappear, the genetic signature of the common guppy is beginning to appear in wild Endler populations due to hybridization.
2005 — Formal Scientific Classification
In 2005, Endlers were formally classified as a distinct species, Poecilia wingei, by scientists Fred Poeser, Michael Kempkes, and Isaac Isbrücker. This officially separated them from the common guppy Poecilia reticulata.
Early 2000s — Rise of Documentation and Formal Preservation Efforts
As preservation awareness and concerns grew over hybridization, the wild-caught Armando Pou foundational stock entered preservation focused breeding programs, notably of Adrian Hernandez (AdrianHD). Adrian’s work encompassed:
Stabilization: Adrian refined and stabilized specific phenotypes like Black Bar, Peacock, Orchid, and others, ensuring they bred true to their wild-type forms.
The ECS/ELAA Era: Adrian was instrumental in developing the Endler Classification System (ECS) along with Guy Smith and the Endler’s Livebearer Association of America (ELAA). This marked the birth of structured lineage accountability, where fish were identified by phenotype and breeder line (e.g., "Adrian Hernandez Black Bar") and breeders were listed in the ELAA Registry.
Understanding the ECS and ELAA:
Think of the ECS as the rulebook and the ELAA as the original organization that followed those rules.
The Endler Classification System (ECS) is the universal standard used to categorize the genetic purity of Endlers based on their lineage and documentation.
The Classification Tiers:
N Class: traceable to Wild collections in Venezuela
P Class: Appears pure, but undocumented
K Class: Known Hybrid
The Documentation Requirement: For a fish to maintain Class N status, it must have a documented "Chain of Custody." In the hobby today, this requirement is primarily met through reputable Breeder Registries that trace stock back to the original wild collections.
The Endler’s Livebearer Association of America (ELAA) was the pioneering organization that put the ECS into practice.
Leadership: Founded and managed by breeder Adrian Hernandez (AdrianHD).
The Registry: The ELAA maintained the primary registry for the hobby. It provided the formal documentation required to certify Adrian’s stock (and those who purchased from him) as Class N Pure Strains, directly traceable to the wild.
Mid 2000s to Present — Evolving Standards
Naming conventions have begun changing to a detailed "Field Format" and the framework for tracing N-Class lineage shifted from the original ELAA registry to modern, ECS aligned breeder registries.
New Naming Conventions: By 2008–2012, serious European preservationists shifted toward a "Field Format" naming convention: Location + Collection Code + (Year, Collector Name). Example: Campoma 29 (2012, P. Voisin). The new format was primarily the brainchild of Philippe Voisin an influential field researcher and preservationist in the modern Endler hobby based in France. The new format has also been gaining traction in some circles in the U.S.
The older initial breeder-line naming conventions are still used in the U.S. especially when properly maintained and documented through breeding registries following ECS. These foundational strains continue to be recognized as stable N-Class Pure Strain lines, even though their breeder-line names emphasize phenotype rather than the newer field format.
The ELAA Registry: The ELAA registry (previously hosted at endlersrus.com) served as the primary database for verified stock during the early registry era. While that centralized site is now inactive, Adrian Hernandez remains the primary authority for these lines. While SwampRiverAquatics.com is Adrian Hernandez’s website, the site is under construction and the registry is not yet public. In the meantime, he can be reached via the 'Poecilia wingei - Wingei's and Endlers Livebearer' Facebook group for lineage inquiries.
The hobby’s primary documentation framework gradually shifted toward ECS aligned breeder registries. ECS aligned documentation (primarily via reputable breeder registries) remains the most widely recognized method for tracing N-Class lineage back to original wild-derived stock today in the U.S.
2021 — Listed as Endangered (EN) on the IUCN Red List
Endlers’ livebearer (Poecilia wingei) is officially assessed on March 8, 2021 as Endangered (EN,Criteria: B1ab(iii,v)) on the IUCN Red List of Threatened Species due to significant threats in its native northeastern Venezuela habitat.
IUCN code meaning: B1ab(iii,v)
B1 – The species has a restricted extent of occurrence.
a – It exists at a limited number of locations or subpopulations.
b(iii) – There is a continuing decline in the area, extent and/or quality of habitat.
b(v)– There is an inferred continuing decline in the number of mature individuals.
The official designation reflects that Poecilia wingei faces a very high risk of extinction in the wild due to a combination of threats affecting its small, restricted distribution. This listing was based on:
Limited and declining habitat: P. wingei is native to a few coastal lagoons and streams on the Paria Peninsula in Venezuela. These habitats are fragmented and degrading.
Habitat loss and degradation: Urbanization, agricultural development, pollution, and other land-use changes have reduced the extent and quality of the species’ natural habitat.
Introduced species and hybridization pressure: The presence of introduced Poecilia reticulata (common guppy) in some waters increases the risk of hybridization, which can further dilute wild genetic integrity.
Small populations and fragmentation: The species’ limited range and small, broken populations make it more vulnerable to stochastic events and ongoing human pressures.
Significantly, DNA Testing of wild populations in Venezuela confirms occurrences of hybridization with released guppies. As a result, many hobbyists and conservationists regard hybridization with released or introduced guppies as a significant threat to the genetic integrity of wild Endler populations, likely rivaling habitat degradation and pollution in its impact. The full extent of this hybridization impact on the genetic integrity of remaining wild populations has not been definitively quantified. This is alarming from a preservation perspective.
2009 Study: In the 2009 study by Schories, Meyer, and Schartl, titled "Is the Endler’s guppy, Poecilia wingei, a distinct species?". Direct quote from the Results/Discussion section of the 2009 paper, the authors state: "Our molecular data also show that in those areas where both species occur in close proximity, hybridization and introgressive hybridization occurs. We found several individuals that had the P. wingei phenotype but the mtDNA of P. reticulata, and vice-versa."
2014 Study: The study shows evidence of hybridization in the wild, at some point, between between common guppy populations and Endlers in the Cariaco drainage, including the Cumaná region. Also, even when the 2 species looked different in appearance from each other, their DNA shows mixing between groups.
The Endler Shop's Preservation Position
At The Endler Shop, we take our role as genetic stewards seriously. Our position is built on four pillars:
Transparent Identification: We clearly label the origin and history of our strains.
Total Separation: We maintain strict isolation between lines to prevent cross-contamination.
Registry Alignment: We adhere to ECS standards, tracing our stock back to wild derived N-Class lines.
Genetic Stewardship: Our Black Bar and Peacock colonies descend from the original Armando Pou / Adrian Hernandez foundational stock.
Because long-term genetic integrity depends on documented origin, a strict chain-of-custody, and total separation from guppy influence, we maintain our Endler lines through established registry systems and disciplined lineage management to safeguard authentic Endler genetics for future generations.
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