My 2022 revised article Guppy Longevity (10 pages) answers the question of why fancy guppies don’t live that long. It puts much of the blame for guppy fragility onto the common practice of using only young fish as breeders. The long-term result is detrimental genetic changes. Since I started using only older fish as breeders, I’ve increased the longevity of my fish from ~6 months to over 12 months. Photo shows a 15-month old male and female. Still room for improvement, but this is progress.