Xipho - Xiphophorus helleri breeding
Xiphophorus helleri is spread in Central America, from Guatemala to north of Mexico. The main variety
is colored in green, the so called green xipho, but due to repeated selections there are plenty of color varieties: red with black tail xipho, read with red eyes xipho, albino xipho, simpson xipho (with a prolonged dorsal fin), tuxeto (with a black longitudinal line), black xipho (from the tuxeto variety, which line coveres the entire lateral part of the body except the fins which remain transparent), berliner xipho (with plenty of black spots on the red background of the body), veiled xipho (with very prolonged paired and unpaired fins).
The female can reach 12 cm length, and the male is a little smaller. The sexual difference is obvious. The male has a modified anal fin, which is transformed into a sexual organ called gonopodium. At veil forms, the gonopodium is very large and the males are `sexual useless`. Another sexual difference is at the caudal fin. The base rays of the male`s anal fin are transformed in a sward;
this gives the name of sword fish. There is a very interesting aspect related to sexual differences and sexes proportions. It`s about the reversibility of sexe and the sexe proportions at spawning. At a certain moment, a strong and well developed female changes the conformation of her body. The gonopodium and the sward appear and she becomes a male. This phenomenon can also take place at other viviparous species, like Xiphophorus maculata. Because of some external factors (pH etc) fisiological changes take place and the female transforms into a male. It is a reversible change, a false male like this can change back to female being able to give birth to fry.