Platy making bubbles at the top of water! HELP!!

[acarl]

I have 4 platys (3F,1M) and an Albino Rainbow shark. My tank has been running for almost a year. Today one of my female platys is staying at the top of the water blowing bubbles and then eating them. She ate this morning just fine, and is not off balance so I am leaning towards it not being swim bladder. She just isn't swimming down and blowing bubbles. Anyone have any thoughts?

 

[Kolykaf]

Have you made any changes to your tank recently? Have you tested your water? The presence of ammonia or nitrite can cause difficulty breathing and cause fish to gasp at the surface where there is more oxygen. Do you notice a change in appearance or behavior in any of the other fish?

 

[acarl]

Have you made any changes to your tank recently? Have you tested your water? The presence of ammonia or nitrite can cause difficulty breathing and cause fish to gasp at the surface where there is more oxygen. Do you notice a change in appearance or behavior in any of the other fish?

No new changes. I did a 50 percent water change 2 days prior to her weird act, but I do this once a month routinely. All of my other fish seemed to be completely fine. I am starting to wonder if it was possibly constipation. The next day she seemed better, and now today is completely normal after a day of fasting. I have noticed they are really pigging out on my driftwoods algae lately so I wonder if she just over ate!

 

[Slaphppy7]

Welcome to TFF

What size tank is this? What kind of test kit do you have?