Hi, I am so sorry to see your Guppy is ill.
Welcome to the community.
Do you know what the water parameters of the tank are?
/Total Dissolved solids
- aka General Hardness and alkalinity or carbonate hardness?
How long have you had your tank running,
how long has this guppy been in the tank?
I would do a partial water change / pwc
, of about 1/4 and then another one of 1/4 right afterwards. This 2 pwc
's are meant to make the chang of water be a little less stressful for the fish, and see if he is feeling any better.
Do you have Prime water conditioner, or which kind are you using?