Swordtails are one of the most popular aquarium fish that can be found everywhere. For several decades, breeders have conducted numerous experiments on the removal of various color variations and shapes.
It was observed that most of the fry preserved the qualities of their parents, which made it possible to create such a wide variety of variations of this representative.
The key point in the successful breeding of the Sword in an aquarium is the separate content of the producers. The reason is that females at a young age can be fertilized by a male and his sperm can be stored in the body of the female until the eggs mature.
Any experienced aquarium finder knows this, just like the fact that if a female has already been fertilized at least once, she can still fry several times even without a male in the aquarium, because she has sperm in “stock “. During the breeding of breeding forms of swordtails, an aquarist may encounter some difficulties, which requires a more careful approach to fish.
Just about such breeding forms and will be discussed below.
Today there is a rather impressive number of swordtail selections, but one of the most popular forms found in our aquariums is the green swordtail with elongated fins. Very often, inexperienced fish farmers cannot get offspring from these fish.
In this case, aquarists are not to blame, because the special structure of the male organ of the males (gonopodium) is to blame.
In the family of the pitsilius, gonopodia is formed from the lower rays of the anal fin. If the breeder was able to achieve elongation of the caudal and dorsal fins, the anal also lengthens.
Unfortunately, an adult male of the green swordtail with such a gonopodium structure will not be able to fertilize females, which makes them absolutely sterile.
It was experimentally proven that there are only two ways of obtaining offspring from these swordtails. To begin with, the female is crossed with an ordinary male swordtail. As a result, you will get offspring, in which about half of the individuals will have elongated tail, dorsal and anal fins.
Then young and mature males are used for breeding, in which the sexual organ has not yet had time to change the structure. Only such males are able to breed.
Unfortunately, almost all females of this form of swordtails are sterile. As a rule, the number of females of black color, capable of breeding rarely exceeds 1 percent.
Reproduction by crossing a black male and a red female is not at all difficult. In the most favorable cases, up to 60% of the offspring will be black and blue.
Only here there is one important moment: the female prepared for spawning should not contact with the “random” male swords, since after fertilization from such males, it completely loses its value as a producer of a strange form. After such an accidental breeding, the female will continue to produce offspring from this chance encounter for a long time.
For this reason, females selected for breeding must be kept separate from the rest.
If the breeder needs to determine the color of the mother of the black-and-blue swordtail, it is quite simple. If the mother was green, the abdomen and head of the fish has a greenish-gray tint, if red, then a reddish tint.
And now a few words about why almost all females of the black-and-blue swordtail are sterile. The reason is that the swordtail has no black natural pigment.
This color can only be obtained by crossing a swordtail with a multicolor patchillian, which has black-blue or black pigmentation on the body.
This color variation was the result of the crossing of the spotted petilla and the common sword. Among the fry you can find individuals that have a black spotted pattern, and it is present only in females.
The fact is that the gene responsible for the spotted black pattern is due to the presence of the chromosome, which determines the female. Accordingly, such a gene is inherited only by females.
If you cross such a female with ordinary red males, then in the litter you can always get a few females and males, who will have the same spot-black pattern.
Unfortunately, amateurs are unlikely to get a new color variation of the swordtail, because in order to get the desired satisfactory result in color and form, more than one mating with the red males is necessary. During breeding work, fish may develop malignant tumor formations that resemble a cluster of black cells on the back of the body or on the caudal fin.
After some time, these tumors are destroyed, which is accompanied by the destruction of adjacent tissues, and the fish eventually die.
The final stage in the selection of fish for breeding is to minimize the number of fish with malignant tumors. In order to continue to work on the selection form, it is better to leave individuals in which the drawing is a scattering of small black dots.
Fish with large spots or black tail fin better to immediately send for culling.