What are some Guppy diseases?

Answer 1

columnaris - A white cotton like fungus on the body, fins or mouth.

fin and tail rot - Ragged look to end of fins and tail, Missing fins or disolving tail.

gill flukes - Fish scratch their gill plates against ornaments or the glass. They may also remain at the surface with gills wide open gaspng for air.

Dropsy - Drastically swollen body with raised scales. This is a very hard disease to cure.

Ich - small white spots on fins and body, looks like fine salt.

Velvet - A hazy white appearance on the body. Ich and velvet are sometimes hard to tell apart.

Shimmy - The fish looks like it is swimming fast but stays in one place.

Intestinal worms - Overall change in color, distended stomach, fish appears to be wasting away.

http://guppyz.tripod.com/guppy_disease_chart.HTML

Answer 2

If its sick it will most likely be less active swim incorrectly or manifest its sickness were you can see it such as discolored spots or small white specks/spots but there are several other visable sickness's if you think your guppy is sick read some fish books are ask a fish vet.