What causes bubbles on top of the water in the fish tank?

[Monica]

It's like an enormous pile of sudsy bubbles, and we can't figure out what's causing it. It's not soap, there shouldn't be any in there anyway. And when the lid is opened the bubbles go away quickly under the open part. What are they from, and how can we get rid of them?

 

[Kim W]

well if you have a betta he's the bubble blower they do this when they are Happy. This is in preparation for an egg bed as if they were in the wild. Some other tropicals will do it also, but don't worry it's a happy fish thing.

 

[Sparrow]

If this is a betta, he's being naughty wink wink hehehe