Understanding Endler classifications is essential when evaluating genetics, purity, and long-term breeding stability.

• Class refers to a fish’s documented lineage and degree of genetic purity. There are three classes, detailed below.

• Strain describes a consistent set of physical traits that reliably reproduce over generations. Check the Shop page for Black Bar and Peacock strain availability. 

• Grade measures how closely an individual fish matches the ideal standard for its strain. Male Endlers are graded, based on coloration, pattern clarity, and overall quality.

  • Grade A: Bold color · Clean pattern · High symmetry

  •  Grade B: Medium Color · Varied pattern · Some symmetry

  •  Grade C: Lighter color · Broken pattern · Low symmetry

Detailed strain and grading definitions are available in the Grading Overview section of the Details page.

Endler Livebearer Classes

There are three recognized Endler classes, each with distinct genetic implications:

• N Class (Pure Strain Endlers): Pure Strain N Class Endlers are fully documented as originating from native Venezuelan populations and are considered genetically pure. All offspring produced by breeding two N Class Endlers remain N Class. Common N Class strains include: Black Bar, Peacock, Red Chest, Double Red Stripe, Snake Chest, Flame Tail, and Center Peacock.

• P Class (Undocumented Lineage): P Class Endlers resemble N Class fish in appearance but lack verified origin or pedigree documentation. While visually similar, their genetic purity cannot be confirmed.

• K Class (Hybridized Endlers): K Class Endlers are known to have been crossbred with other livebearing species, most commonly Poecilia  reticulata (guppies). These fish display a wide range of traits and are clearly not Pure Strain Endlers.

Why Most Pet Store Endlers Are Not Pure Strain

When Endlers appear in pet stores, they are almost always classified as P or K Class, due to the absence of verified lineage documentation. True N Class Endlers require careful record keeping and controlled breeding, standards rarely met in commercial mass production.

For detailed explanations of Pure Strain N Class documentation, key differences between N and P Classes, and in-depth breakdowns of Black Bar and Peacock strain grading, please refer to the Details page.

Pure Strain N Class Endlers represent the last genetically verified link to wild Endlers. Because Endlers are likely extinct or hybridized in their natural habitat, maintaining N Class lineage is vital to preserving their original colors, patterns, behavior, and genetics exactly as they existed in the wild. This is especially critical given Endlers (Poecilia wingei) formal IUCN Red List classification as Endangered in their extremely limited wild native range in Venezuela.

Unlike P Class or hybridized Endlers, N Class Pure Strain fish are documented through an unbroken registry tracing their lineage back to original collected wild stock several decades ago. This documentation protects against hybridization and ensures  genetic integrity across generations. For additional in depth documentation information, please refer to the Pure Strain N Class Documentation section of the Details page.

Why hobbyists choose N Class:

• Preserves authentic wild genetics

• Displays deeper, metallic coloration and natural behavior

• Provides stable, predictable breeding outcomes

• Protects endangered genetics for future generations

Choosing N Class isn’t just about owning beautiful fish — it’s about conservation, credibility, and preserving living history.