Hello everyone, Guppy is actually a very hardy fish. I have been keeping aquarium fish for about 10 years and during this time I have never had guppies sick, they are able to withstand any water temperature and are not afraid of dirty water in the aquarium. Perhaps in your aquarium some kind of parasite from which guppies die. By the way, I can recommend that you look at these
guppy diseases with pictures, perhaps in this way you will be able to find out what the problem is.