Betta building bubble next in co2 bell dangerous?

[Daave]

so i have the ISTA passive c02 diffuser kit in my tank, and my Betta has decided it's a great spot to build his bubble nest, which means he's sitting in there and gulps the co2 to make bubbles with. this has me a little concerned and i'm wondering if i need to adjust the bells so he can't get into them anymore.

any thoughts on whether or not this is bad for him?

[Fish Folk]

1 hour ago, Daave said:

so i have the ISTA passive c02 diffuser kit in my tank, and my Betta has decided it's a great spot to build his bubble nest, which means he's sitting in there and gulps the co2 to make bubbles with. this has me a little concerned and i'm wondering if i need to adjust the bells so he can't get into them anymore.

any thoughts on whether or not this is bad for him?

Hmm... well, anabantids can process oxygen both through their gills and through their labyrinth. It seems odd... but if he’s Ok, he probably will be.

But you might consider selecting some other option for him to build under / on. Catappa leaves that float are sometimes favored. A few Bettas may work around water lettuce or hornwort.

The breeder method is to place something like a styrofoam cup with the bottom cut off—a tunnel-like space  where he can build without any fear of surface disturbance.