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Compatible Guppy Strains

by Jim Alderson, DVM


Just about every PPGA meeting I will bring a trio of fish for a new member. After handing the fish over to the new guppy enthusiast, one of the first things they always ask is "Do you think these will cross well with that pink fish that I purchased from the store last month?" Never mind the ten years of careful linebreeding used to reach this stage of development. It usually takes us one year to prove to the new members that outcrossing the fish willy-nilly doesn't work!

When making outcrosses you want to cross with lines that you are pretty sure are going to give the desired results. Somewhere around 80% to 90% of outcrosses produce fish that are inferior to both parents. When you are selecting which strains of fish you would like to work with, it is advantageous to select lines that can be used to improve each other. Over the years I have kept a mental catalog of the crosses that have worked well. Today, these crosses are the backbone of my breeding program. Below are some of the crosses that have worked well in my fish room using my lines. These are pretty well tested crosses so they should work for most lines of these colors.

Reds and H/B Reds: I will use the gold bodied red males into the gray bodied h/b red females to improve the h/b reds. First generation will give 100% h/b reds. These are show stoppers. I then discard all the females from the cross and breed the males back to the pure gray bodied h/b red females. The downside of this cross is losing the deep h/b body color in the males. Always select the females with the darkest body color. (Note: you can create an excellent gray red line by saving some of the F1 females and crossing them back to the pure gold red males. The resultant offspring will be 25% gray reds.)

Reds and Albinos: I will cross the gold red males into the albino females to improve the albino line. The F1 is 100% gray reds. I then take these gray red males back to the pure albino females. Theoretically you should get 30% albinos, but I usually end up with 25-30%. You can then brother/sister these again for about three generations without much loss in vigor or fertility. Purples and Greens: One of the best kept secrets in the hobby! This cross works both ways and will produce some excellent blues as well. The purple is dominant and will darken the greens considerably. With this in mind, use the lightest green colored male into the purple females to produce bigger and better greens. To improve the purples, cross the purple males into the green females. To select the grown females from the hybrid cross, shine a flashlight on them at night with the lights turned off. The green females will have a green crescent at the base of the peduncle and the purple females will have a purple crescent. Variegated Yellow Snakeskin and H/B AOC (leopard): To improve the pattern in the h/b Aocs, cross the snake males into h/b females. In my lines the h/b is X linked and dominant. This means that the resulting offspring will all be h/b. Take the best male from the cross and breed them back to the pure h/b females. I use this cross about every 5 or 6 generations in my h/b aoc line.

H/B Pastel and Pastels: To improve the size and finnage of the pastels, cross a gold bodied white pastel into a gray bodied h/b pastel female. The offspring from this cross will be washed out gray bodied h/b pastels. Take the best of these males and breed them back to the pure gold bodied pastel females. The offspring will be 50% gold bodied pastels. These will be bigger and more vigorous than the original pastel line.

Blue/Green Bicolors and Yellow Variegated Snakeskins: Take the largest blue/green male (don't worry too much about the color pattern) and cross this fish with the snake females. Take the males from this cross and breed them back to the bl/gr females. I have some excellent bl/gr bi's coming up from this exact cross.


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