@vekta Said
Heavy breathing in any bird is not a good sign. If you let him out to fly around he might land and breath heavy for a few seconds from being out of breath after a long flight. Other than that he shouldn't have trouble breathing.
Birds tend to be very good at hiding the fact that there is anything wrong with them. So once you notice heavy breathing or lethargy you need to get him to an
Avian veterinarian.
Just changing his water and cleaning his cage his not enough. You need to dust and clean the entire room that the cage is in but not with modern chemical cleaners. If you do you need to move him out of the room until the chemical smell goes away.
I use a mixture of water, white vinegar, baking soda and lemon juice as an all purpose cleaner in my room. I actually took out the carpet and installed tile floor mostly because of my birds. Carpet holds a lot of dust and crap which was making my birds sneeze a lot. I don't have a canary in my collection but your bird's environment is not limited to what's inside the cage. It's not really species specific just common sense if you plan on letting your bird have free flight time outside his cage.
If he is having trouble breathing you need to take him to an Avian Vet, first available appointment you can get.
Good points. Also, birds are very sensitive to most air fresheners. Anything like this cause respiratory problems. I used to have canaries though and they do make a normal clicking sound from time to time.