Personally, I would not medicate fish that aren't showing any obvious symptoms. There are way too many different things that can be wrong and many medications have side effects.
Breathing heavy at the top of the water almost always means there is something wrong with the water or that it is not right for the specific fish.
We need more details.
What are the readings for ammonia, nitrite, nitrate, ph, gh
and temperature. How long have you had the fish? What else is in the tank? How big is the tank? How did you acclimate the fish from the old water to the new? What kind of filtration is on the tank? What are you using to condition the water?