How do you tell if a guppy is dying?

Simple observation will tell you the fish is dying. If it is what are you doing wrong? The rules for keeping fish are. :- 1 inch of fish needs at least 1 gallon of water but more is better. :- Every tank needs a permanently running cycled filter. :- Every tank needs at least 50% of its water replaced every week.Follow the rules and you stand a chance of keeping fish successfully. Miss out on any of them, and I can guarantee that your fish will have constant health problems.