the so called hardy guppy has been my bogey fish.
Right from the first worm infested guppy that was sold to me to the more recent imported guppies that carked it. (no not my lovley HFF one, they're doing great) I only seem to have guppys die on me!
Conversely my Kuhli loaches who i got a week after setting up are amazing little things that have survived a cycling tank, numerous trips up the filter, escaped the worm problem, put up with bullying by the BN's, endured a shift and two tank moves, one was a temporary carpet fish, were not affected by whatever disease those imported guppys bought into the tank, escaped the recent ich and were unharmed by any of the medications I've used in my tank. Great little guys who come out every day to let me know they're fine.