Guppy Japan Blue and Japan Red

24. September 2021

There is a number of tail fin shapes of the guppy, which have been standardized by the guppy breeders. As a rule, however, these breeds are only found at private breeders. In the pet trade the triangle guppies dominate in such a way that aquarists, who do not inform themselves specifically about guppies, could get the impression that these are the “normal guppies”. Recently, however, there has been a move away from this trend.

Double sword guppies are an old breeding form. Already in many wild guppies you can see hints of lower or upper swords – that is a pointed extension of either the upper or the lower tail fin edge. By appropriate breeding selection the double sword can be developed. First reports of double swords date back to 1928, already some years earlier animals with clear predispositions to the double sword appear in illustrations. In contrast, the triangle guppies, which are so dominant today, did not appear until the late 1950s and early 1960s.

Interestingly, however, the double sword was a direct predecessor of the fan tails, from which in turn the modern triangle guppies were bred. The fantail – as can be shown by crossbreeding experiments – is a double sword, so to speak, in which the space between the swords is filled with fin material. The tail fin shape “fan tail” comes from the combination of a certain color gene with the gene for double swords.

One of the most popular double sword guppies in the trade is the beautiful “Japan Blue”. While the name actually refers to the coloration and could be bred on other fin shapes, only specialized guppy breeders usually do. Supposedly, the Japan Blue is called this way because the color is said to have first appeared in feral free-living guppies in Japan. The color is inherited from the male (it is linked to the Y chromosome).

Quite new is the Japan Red, which should actually be correctly named Japan Blue Red, as it exhibits the typical Japan Blue cover sheen, but on a red and gold base coloration. The Japan Red is also bred as a double sword.

For our customers: Japan Blue has code 419043, Japan Red code 419047 on our stock list. Please note that we only supply wholesale.

Text & photos: Frank Schäfer