Category: Outcrossing Guppies with Endlers

Endler Guppy Cross

Preliminary results from crossing my Rainbow guppies with Endlers (Santa Maria strain) turned out much better than I expected, especially for the male Rainbow X Endler female matings. See photos of hybrid males at 3.5 months. LOTs of color! Females are also nice in that they have plenty of pigment in their caudal and dorsal fins, which the Endler females did not have. [Progeny from reverse cross (male Endlers X Rainbow females) were not nearly as attractive.]

I did this outcross, because my Rainbow guppies have had fitness problems last 2 years, probably due to accumulated inbreeding. Hopefully, infusing genes from these hybrids into my Rainbow stock will help prevent fluke outbreaks and increase longevity. Long-term project…

Outcrossing Guppies with Endlers

In November 2025, I gave a talk to the Bucks Co. Aquarium Society in Pennsylvania. Great club! During their auction, a bag of pretty Endlers caught my eye. I purchased them and am now crossing them with my Rainbow guppies. Goal is to increase the fitness of my guppies. [Forthcoming article in ALA newsletter (American Livebearers Association) explains why.]

All the females I used for the outcrosses were non-virgins with stored sperm, so I had to carefully pick out progeny that were truly F1 hybrids.   Good thing, because the first, early batches were mixed (hybrids and non-hybrids).

For the Endler male X female guppy cross (Photo), I picked out young female progeny with clear tails, a distinguishing feature of Endler females. So I was able to collect 5 nice virgin females from mating Endler males to a top Rainbow female.

Top Rainbow female guppy with young male Santa Maria Endlers. (This Endler strain is itself an Endler/guppy hybrid.)

For a reverse cross, I mated my best Rainbow males to Endler females (Photo). I identified hybrid females as Rainbow-sired by their darker, pigmented tails.

Top Rainbow male with Santa Maria Endler female.

This is a long-term project.  So far, I am pleased with the progress.  When I began, I was not sure how to identify hybrid females.  But now I have 5 very fine  virgins from each of the 2 outcrosses.  I plan to mate them to my best young Rainbow males.