Good luck.
Found this for you as well, but not the writer of this information below.
Oxygen Deficiency
Symptoms:
Fishes that suffer from oxygen deficiency exhibit increased breathing, restlessness, and hanging under the surface of the water, gasping. Oxygen deprived fish usually have an overall pale coloration. Fish that die from the condition are usually observed to have their mouth open, in addition to exhibiting pale skin and gills.
Cause:
Lack of oxygen. This could be due to one or several factors: overcrowding, heavy feeding, dirty filters, poor aeration, a small water-to-air surface area, polluted water, elevated nitrite levels, and excessive algae growth or too many live plants. This last factor may not seem a logical one, but in the dark, plants and algae actually take oxygen out of the water, giving off carbon dioxide just as the fish do. Only in the presence of light do they release oxygen. Consequently, if you find your fish gasping at the surface in the morning, you may find you have too many live plants or too much algae in your aquarium.
Treatment:
Perform an immediate water change and increase the aeration in your tank. There are several methods for increaseing the water movement in your tank. This is important to ensure that your fish are getting the oxygen they need to stay healthy.