Betta bubble nest

[Maeve]

Is my daughter's Betta just building massive bubble nests or is something up with the water? 

[FLFishChik]

How old is the tank? Generally (in my limited experience) Betta form bubble nests under leaves or floating plants/decor in the tank. From what I see, it looks far too large an area to be a bubble nest and more likely to be protein bubbles. 
  Over feeding, not enough surface agitation, decaying food/organic matter in the water, dirty filter can all cause this. If you look st the surface of the water at a slight angle and notice a “rainbow-like” or oil slick looking substance, then protein build up is most likely the issue. 
  Adding an air stone if you don’t already have one could help. Also decreasing the amount you feed each time and making sure to removed anything uneaten afterwards as well as removing any dying or decaying plant matter will help to.