Maybe 5 years ago I imported some trios of “high dorsal” guppies from Thailand. It might have been the type listed on this website. Then I lost this line after an unexpectedly cold week in Arizona. A sudden drop in water temperature can wreck a guppy’s immune system.
I really love that type of guppies, and I don’t think I’ve even seen anyone raising them in the US. Anyhow, I have a tank full of a lot of various male swordtail guppies. And I noticed there was one male guppy that was born without a sword. So he looks exactly like several other males, only a clear roundtail instead of a swordtail. A few weeks pass and I didn’t really give it much thought. Then it occurred to me, I’ve accidentally created a “high dorsal” guppy. So I pulled this guppy out and put him in a tank with a couple regular sword females. I expect to get a mix of tail types for a generation or two. But if I keep pulling out any guppies born with swords, I might be able to turn this into the “high dorsal” line I’ve wanted.