Basically we have 3 different methods of breedings, line breeding, in-breeding and outcrossing.
In-breeding – Breeding of closely related fish, like brother-sister, father to daughter, son to mother etc. This technique would work well provided care is taken in choosing the right breeders.
Line-breeding – Widely popular among breeders, here you would start with a male and breed him to 2 of his sisters, drops from them are raised separately (these become 2 different lines) and bred brother-sister for 3 to 6 generations, then you would cross a male from one line to another and vice versa. These again would be kept separate and the same rule followed. Again careful selection of males and females as Breeders is very important. This is similar to in-breeding, but you are running 2 separate lines of fish which are closely related, this way you could retain better qualities for long period of time.
Outcrossing – This is basically crossing 2 guppies which are not related, this would result in a hybrid guppy with much vigor, size and color. The could result in outstanding show fish. Many breeders do this, but again, one should be educated well enough in guppy breeding to do this, careful selection of fish to outcross is very important, again, you cannot cross a black to yellow and expect outstanding fish, the outcross has to be with compatible colors( we will explore this later in one of other articles), for now, think this, like green to HB green, green to purple, blue to HB blue or blue to purple, red to HB red or red albino.
So there you have it, the basic methods of breeding. So one can manipulate the above breeding methods to produce good fish. Again careful notes and photos should be kept to document what worked and what did not. Other terms you will hear about breeding are community breeding, harlem breeding etc.
Personally I follow some of the breeding strategies above and different variations of the above to produce my fish. When I am maintaining a line, I will probably go with 2 males to 3 or 4 females, when I am trying to improve a line, I normally go with one male to 3 females. Females play a very important role in your breeding program, some breeders don’t give enough time or enough space for females, females does affect the color and shape of off spring contrary to belief that they wont. They also play important role in body size. Also one important tip, keep look out for what i call “supermale” among the males, this fish can be categorized as something which is close to being perfect in most of the aspects.