The first photo is of a male Flame Variatus and the second of a female. This is a commercial (domestic) strain of Xiphophorus variatus. Like most commercial xiphophorines (swordtails, platies, and variatus), this fish is likely to be of hybrid origin, although the strain clearly is primarily X. variatus based on its fins and shape.
In previous blogs, I wrote about developing our Redtail Black Variatus strain from some nondescript Tuxedo Variatus we had acquired from a Florida fish farm; then from those fish developing our Redtail Blue Tuxedo Variatus; and from them our Redtail Blue Variatus. This blog concerns the creation of our Flame Variatus from the latter fish.
In April 2012 I was selecting breeder Redtail Blue Variatus when I noticed two males in which the red from the caudal bled into the caudal peduncle. Thinking that was a nice variation, I set them up with about twenty Redtail Blue Variatus females. I purged the first month’s worth of fry since they were from other males. I grew up the next batch of fry, most probably from these two males. I was surprised to find some males whose back halves were a bright orange. More intrigued than ever, I took the best two and gave them some sisters or half-sisters that showed some orange in their bodies. The next generation had more orange. I selected the best of these as breeders. Among their offspring were a few fish resembling the photos. From that point all I had to do was select the best fish each generation to yield Flame Variatus. The strain is set and we are now offering this fish for sale.