The reason they are at the surface trying to breathe is due to a lack of dissolved oxygen in the water. The low levels of oxygen are mainly due to a lack of aeration or poor water quality, which can then cause the fish to stress. ... Fish need different amounts of oxygen depending on the season.
Do goldfish need to surface for air?
As it has been stated, goldfish do not always require an air pump to survive. It can do well in a tank that is well oxygenated for as long as it normally can. As long as there is enough surface movement that translates to oxygen, then the goldfish can live just fine without an air pump.
Is it normal for goldfish to surface?
Lack of oxygen in the water will cause your fish to swim to the surface to breathe; the concentration of dissolved oxygen is highest here. As soon as you notice that most of the fish are gasping for air near the surface, act immediately because this is a clear sign of distress.