Genes/Colors and their location:
Body colors (all autosomal) are:
– grey – dominant over all over body colors
– gold/tiger/bronze – recessive
– blond/gold – recessive
– albino/rrea – recessive
there are two different genes which cause the albino phenotype and which can’t be differentiated.
– lutino/wrea – recessive
– there are three types of blau:
one blau –gene shows no red and no yellow
another blau gene could show reduced red but no yellow
and the other blau gene (this one is called “hellblau”, this is a German word which means light blue) could show yellow e.g. snake skin
is something special because of its peculiarities, it has a reduced number of the big black colour cells (melanophores) and it looks like tiger in its pure manifestation (without the hb). In the combination with the Nigrocaudatus 2 gene (it’s the gene for half black/tuxedo) the back becomes pink, that was the reason for the name “pink”, because the first guppies with this body colour where pink half blacks. It is suspected that they have also an increased number of iridophores. – cream – double recessive, gold + tiger
– white – double recessive, blau + gold
– silver – double recessive, blau + tiger
– “super white” – triple recessive, blau + gold + albino
you can breed more combinations but only for these double and triple recessive body colours exists a specific name.
Some (not all!) colors:
1. colors for the fore-body (the belly, until the beginning of dorsal in their original appearance):
– Coral is a metallic red which is in most cases y-linked but there should be one x-linked strain in Germany too.
In Germany we call it “neon” . In the combination with one of the blau genes it becomes light blue.
– Moscow is a y-linked gene in most cases but there are some x-linked strains too.
It is a metallic silver until dark blue colour. The intensity depends of the mood of the male. You can find this gene in metal heads (y-linked moscow + y-linked snake skin) or moscow blues (y-linked moscow + y-linked blue + x-linked blue) or in moscow greens and moscow purples
– Schimmelpfennig Metall (this is the original German name)
or platinum is a metallic white/yellow/bright purple/bright blue. It is y-linked in most cases but there are some x-linked strains e.g. in Japan too.
– Lazuli is a light blue which is y-linked (I don’t know it for sure,
because only the Japanese breed it and in Europe there are no lines of this strain, so I had to use a online-translation which could be wrong)
2. colors for the lower-back:
– half black (it is the Nigrocaudatus 2 gene)
is a x-linked gene in most cases but there are some y-linked strains too. It is a more or less black colour. It could become dark blue too after some selective breeding ( you have to increase the number of iridophores which lay above the melanophores) . In combination with the platinum it seems to be greenish.
– japan blue/aquamarine
is a light blue which is a y-linked gene in most cases but there are some x-linked strains too.
– Störzbach (Stoerzbach) metal is a recessive and autosomal metallic blue,
but in combination with other colour-genes it makes them a metallic colour e.g. Mikarif (Stoerzbach metal + snake skin)
There a lot of colours which consists of several different genes for example full reds. There are 6 (perhaps more) different genes for red and they can be y-linked, x-linked and autosomal, some are dominant and others are recessive, so it’s very difficult to talk about reds and full reds. Some colours are shown on the whole body e.g. snake skin. And some colors are shown on the body and the fins e.g. blues (in blue delta IFGA strains), parrish and hutter greens, snake skins, reds, purples, 3/4 blacks etc.
The problem is that some body-colours or normal colours also effect the form of the caudal e.g. you cannot create a half black double sword. There are some genes which are not really a colour like red, but the effect the caudal form too. The x-linked gene “cp” is such a gene. It causes a dark pigmentation of the caudal and together with the “double sword-gene” it causes a delta tail. The delta tail always consists of two or more genes. There has to be the “double sword-gene” (which can be y- or x-linked) and a colour gene for the caudal. Sometimes the male has both necessary genes or the female has both genes or each sex has only one of these genes, but in all these case you got a delta tail.
I hope you can see that the genetic of the guppy is very complex and to create a new strain is a lot of hard work and a great challenge.
when your cross a grey guppy (GG) with a gold guppy(gg),
your will get guppy of these four different genotype (GG), (Gg), (gG) & (gg).
All 3 fish with genotype (GG), (Gg), (gG) will turn out to be a grey guppy,
in this case gene (G) is considered dominant over other gene (g).
Recessive – A gene in which the trait it represent will not show
because its dominanted by another gene it pair with is considered recessive.
Refer to the example above,
those guppy with genotype(Gg) will turn out to be grey instead of gold
because the gold gene (g) is recessive.
Only instance when you can have a gold body guppy
is when the guppy have this genotype (gg).
Homozygous – Paired genes that are the same at the same locus(location). Using the above example we can say that a gold body guppy have homozygous gold body trait.
We commonly refer a heterozygous guppy as one that does not breed true.
Heterozygous – Paired genes that are different. Referring to the example above, the grey guppy with (Gg) & (gG) genotype are heterozygous.
We commonly refer a homozygous guppy as one that breed true.
Only the male can show y-linked traits.
But they can also show x-linked taits or a mix of y- and of x-linked traits.
Y-linked means that the gene(s) for this trait are on the Y-chromosome.
It’s the same with x-linked. Females can’t show all traits because there is a lack of some special colorcells in their skin. They have all kinds of colorcells but they have less cells of certain kinds than the males.
If a y-linked gene becomes x-linked because of a crossing-over the appearance of the phenotype of this trait on the females could be the same as on the males. But sometimes there are some changes in the appearance e.g. japan blue. Females with x-linked japan blue don’t show any blue on the body, they only show sometimes some blue on the caudal. Don’t ask me why they don’t show it. Full gold females show that females have enough iridophores to show metalic colors. You see the same genotype (same genes) doesn’t mean the same phenotype (this what you can see with your eyes if you look on the fsih) at both sexes.
It’s like every science: there are more questions than answers and even if got the answer to one question there two new questions in this one answer.
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 nave 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 bis coming up from this exact cross.
Source; Fish Forums