blond snake endlersCreating an Endler Hybrid is Relatively Easy

Endlers & Guppies both produce a drop of fry in less than a month.  These fry can then produce their own fry within a few months.  This give you an ability to see the results of your labors in a relatively short time frame.

Of course most of the time it’s not just a matter of putting together a guppy and an Endler and ending up with a new stable Endler hybrid strain.  You will want to look at the results created by your hybrid and use specialized breeding methods to bring out the traits that you desire your new hybrid strain to have.

Making Room

If you plan to create a new hybrid strain you will usually need quite a few tanks.  The number of tanks required depends on the breeding techniques you choose to use.  Many breeders minimize the number of tanks and have greater success if they focus on one specific trait at a time.

Guppy / Endler Breeding Techniques


Inbreeding often is thought of as a bad thing when breeding fish however it is a very common and widely used technique.  It is often used when developing a new and unique strain.

Inbreeding involves a process of selecting a fish that has the properties you wish to pass on and pairing it with a suitable mate.  After fry are produced the mate is removed and replaced with fry that are of the same sex as the mate that they are replacing.  These fry should exhibit if possible the trait that you wish to pass on.

The process is continued until you have the result you desire.  This process can be continued until the resulting offspring are nearly clones.

One word of caution when it comes to inbreeding.  You must be very careful when selecting your stock used for inbreeding.  Traits both good and bad will be past on to future generations.  Any weaknesses or deficiencies found in your original stock will be passed on.

Line Breeding
Process used to line breed Endlers using two separate pairs.

Line Breeding or Line Crossing

This process is often used when maintaining an established strain.

Line breeding involves a similar process as inbreeding except with more than one pair.  This process generally produces healthier offspring however you must start with healthy high quality stock.

In the image to the right we are showing the method we used to line breed  with a minimum of two pairs.  The pairs (P1) are allowed to breed and the resulting offspring are placed in a separate tank.  These offspring (F1) are allowed to breed.  The offspring of F1 is then placed in a new tank.  These offspring are F2.  We continue the process for another generation and get F3.

The F3 males are then crossed with the F3 females from another line and the females from the first line is crossed with the males from the second line.  The the whole process starts all over again.

This process is continued indefinitely.  The offspring selected should be healthy and have specific traits that you are trying to breed for.

As you can see from the diagram, this process requires a large number of small tanks.


Outcrossing is basically the opposite inbreeding.  This process basically produces hybrids of the original two strains.  It is a process that may or may not work depending on the compatibility of the two strains being crossed.

The process of outcrossing can produce dramatic results fairly rapidly and can produce results that may not be possible with inbreeding or line breeding.

For example you may want to breed for a specific dorsal fin size or color.  When you breed one strain with another strain you may get what you desire or you may get something altogether different.

If the two strains are compatible you will likely get 25% of the offspring to have the specific trait you are working towards however often the specific trait doesn’t show up in the F1 cross at all.  If the trait does not show up at all then you would want to breed the offspring with the fish you are trying to get the trait from.

If the trait is recessive you wont see any results until the male and female fish both carry the recessive gene.

If you do have offspring that end up with the specific trait then you can will want to breed continue the process in a similar manner as you would with inbreeding until, if you are lucky, you end up with the desired result.

You would then want to breed back your hybrid strain to your original strain to help stabilize the strain.  This may pose some additional challenges as you may imagine.

Remember that you need to be extremely careful what pairs you start with originally as other traits will be passed on as well.

This is a very simplified explanation of outcrossing.  For a more in depth explanation of outcrossing and the complication you may face you may wish to read “How To Outcross Guppy Strains” by Midge Hill.  

Maintaining your Endler Strain

Whether you are breeding pure Endler or hybrids you will want to continue the breeding process to keep your strain looking it’s best.  Without proper breeding techniques most Endler or Guppy strains can revert back to looking wild within only a few generations.

Responsible Breeding

Creating your own Endler/Guppy hybrids is relatively easy however it should be done responsibly.  If you choose to create a hybrid strain it is very important that you disclose that your Endler is a hybrid or K Class strain.  This helps keep the pure Endler strains pure by helping to prevent cross breeding pure Endlers with hybrid Endlers.

Improving Guppy Genetics

One of the advantages to crossing Endlers with guppies is the addition of new genes to the often weakened Guppy genes.  Over the years Fancy Guppies have become so inbred that many of the strains have become weakened.  These weakened Guppies become ill much easier and are susceptible to conditions such as Scoliosis of the spine.

The addition of the new Endler genes seem to greatly improve the health and hardiness of Guppy hybrids.