I have a 55 gallon tank with 5 parrot fish. They are all swimming at the top gasping for air. I have been out of town and my husband says they have been doing it for several days. I cleaned their filter last night and they seemed to be better. Tonight they are back to gasping at the top. I have tested the water levels and nitrites, nitrates, PH, and ammonia are all normal. They are normal in color. The tank has been slightly neglected due to the fact that i am 9 months pregnant and it does need some attention. But like i said water tests normal. What could be wrong with them? Thanks for your help in advance. My toddler loves the fish and we would all be so sad if something happened to them.