Freshwater
What else would you expect them to swim in? Of course Goldfish swim in water.
Yes, actually it must be in water. If the goldfish is not in water, it will die due to suffocation.
Cold water.
change water
Goldfish make bubbles on the surface of the water by releasing air from their swim bladders through their mouths. This process is called "gulp breathing."
No
Unchlorinated water, such as bottled distilled water is best.
A goldfish is not from the fish type of anabantid (labyrinth fish) who would actually really drown if they do not swim up to the water surface to breathe.
A damaged swim bladder.
Goldfish make bubbles because they release excess air from their swim bladders, which helps them regulate their buoyancy and stay balanced in the water.
The same reason you run more actively with air in the atmosphere. Without air, and therefore oxygen, you and the goldfish will suffocate, making it difficult to swim or run.You take in oxygen through your lungs; the goldfish takes in oxygen through its gills.
they are most likely looking for food sources as algae normally builds up in that kind of area and like water snails fish will eat algae!