Line Breeding Endlers…The Casual Hobbyist Approach

Strains and Variations of Endlers

Endlers grow fast and young fry can be bred as early as a few months after they are born. Female Endlers can drop fry every 26-30 days. Due to these factors several generations of Endlers can be raised in a relatively short period of time.

One of the interesting things about Endlers is that most of the traits carried by the females are recessive. If you were to take a male from a pure strain of Endlers and mate it with a female of another pure strain of Endler the resulting fry will nearly always look like the male Endler. If you continued to keep the Endlers for several more generations you may see some fry from the female strain start to show up several generations later.

Snake Pattern Orchid Endler
Snake Pattern variation on an Orchid Endler

Often unique fry are born that differ from their parents. These unique offspring are known as variants. Nature uses variants to help ensure the survival of a species. Variations that help a species to survive are often passed on to future generations. Those variations that don’t help improve the survivability of a species are usually lost and are not passed on.

Because generations of Endlers can be raised in a relatively short period of time and variations are relatively common in Endlers this creates a unique opportunity for those that wish to produce new and unique strains of Endlers.


This differs from those who create hybrids. Hybrids are created by crossing one species with another such as crossing Guppies with Endlers. While most hybrids result in offspring that are not fertile and cannot produce young, Endlers crossed with guppies do produce fertile young. Many beautiful new hybrid Endler strains have been created over the last few years.

There is nothing wrong with creating these wonderful new strains of Endler/Guppy hybrids so long as those creating them don’t try to pass them off as “pure” Endlers. These crosses should be classified as K class Endlers. This helps protect the pure strains of Endlers (N Class) from being contaminated by hybrid strains.

Once a hybrid has been created the future generations can never again be pure Endlers. This is why Endlers classifications were created.

Swordtail Ender
Orchid Endler that has been line bred for a very long sword.

How to Line Breed Endlers

Creating a unique pure N class Endler strain is fairly easy if you are patient, lucky and follow some simple steps.

If you would like to produce your own line of pure N Class Endlers here is the very simple method we use.

Step 1: The first step is to find a male fish that has specific qualities that you wish to pass on to future generations. This may be unique colorations, specialized fin shapes, or other unique characteristics you wish to pass down to future generations.

Step 2: Match this male with a female that is very healthy and has the features and body shape you wish to produce.  This female should be virgin.  This pair we will call P1.  The problem with just picking out a nice female from your community is that females can become pregnant at a very young age and one “visit” from a male Endler can result in several months of pregnancies.

Simple Line BreedingTo prevent diluting our work with genes from our community tank we select females from our fry that have never been introduced to an adult male at an age that it is just possible to tell if they are females. At this age it is still possible to accidentally select a slowly developing male so we keep these females separated for a month or so until we are sure we only have virgin females.

You should have at least 2 P1 pairs.  Note:  This process will require a quite a few tanks.

Step 3: When the young female fry grow up and produce fry themselves take the fry out of the breeding tank and place them in their own tank.

Once the fry are old enough to distinguish sex separate the males from the females.

Step 4: When the fry grow up to the point that you can see which ones are the best according to the end result you are looking for, pick the best female and best male.  This will be pair F1.

Do the same with your additional line(s).

Step 5:  Continue the process until you reach pair F3.  The fry produced by pairs F3 will be separated like normal however this time when you create the new pairs place a female from one line with the male of another line and do the same with all of your lines.

This will become the new P1 and the whole process starts over again.  This will help keep your Endlers genetically healthy as you breed them.

As you can see, the process takes a lot of tanks and a lot of patients.

It is easiest if you breed for one specific trait and when your line is consistently producing the desired trait then you can focus on a different trait.

You may wish to completely separate the males altogether in their own tank as we do. We do this because we want absolute control over the breeding of our Endlers. Every once an a while a male will be born with little coloration or poor markings. These are males you definitely do not want to be contributing to the gene pool of your Endlers.

Allowing these poor quality males to add their genetics to your community of Endlers can eventually dilute the colors and beauty of your Endler community.


Is That It?

This is a very simplistic method of line breading your Endler’s.

In most cases if you take a female Ender of one strain and pair it with the male of another strain the resulting male fry will look like the male parent.  However a few generations later you may see some offspring that look like the original strain of the female Endler.

Another consideration after line breeding Endlers it to make sure that the strain does not become too weak from the line breeding process.  Always try to make sure the Endlers you choose are healthy and have the specific traits you are looking for.

After several lines have been crossed you may wish to add additional Endlers from a separate pure gene pool to help keep the strain strong, healthy and beautiful.

Pure N Class Orchid Endlers that have been line bred to produce extra long swords.


4 Responses

  1. lilo

    That’s a very useful bit of info that many of the traits in the female are recessive. This is important because even now, you can not get pure strain females – too many breeders hang on to them to prevent people from doing exactly what your article is about.

    • Marty Andersen

      We have always offered females to our buyers. We do this because we understand the importance of having high quality pure stock available to hobbyists.

      Of course our female Endlers are higher priced than our males as it is difficult to keep them in stock and most of them are offered in our pairs or trios.

      Much of our “competition” are hobbyists that purchased Endlers from us and are now breeding and selling their Endlers. Many of these hobbyists have become our friends over the years.

      As someone who sells Endlers online there is always a risk of someone mass producing Endlers and undercutting our prices.

      While we know there is a risk it is not really a fear of ours as we understand that it takes more than just breeding them to get high quality Endlers. Purchasing high quality stock is only the first step in producing high quality Endlers.

      Those who buy Endlers from sources that mass produce them run the risk of getting diseased, weak, low quality fish which are likely to have been hybridized with guppies.

      Low quality massed produced Endlers are a poor choice for those who are serious about breeding Endlers as it is impossible to breed high quality pure N Class Endlers from low quality, undocumented stock.

  2. Justin

    Does the line breeding process essentially shorten the time frame for observable traits to be cultivated in that line? The process shown above provides for a swap at F3. If a single allele is showing up with that line, aren’t you basically shortening the time frame you have to work with that allele by crossing the females at F3? Would it not be better to cross later on down the line?

    • Marty Andersen

      Yes you are correct if you where attempting to modify the strain for a specific trait. The above example would be used if you had a strain that is stable and you wanted to keep it that way for a very long period of time.

      Crossing later on down the line would be a form of inbreeding that would give more time to work on a specific allele.

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