one of my female bettas has recently been floating at the surface. always straight up with her head towards the surface. i can't really tell for sure,but her her body (near her head) looks like it's swollen or something.

tank: 10 gallon
filter: power filter
fish: 2 male bettas,3 female (divided)

i keep the ph about 7.0

Have you tried fasting them for a day or two and see if that helps? She could be constipated. Then you could try to feed her a bit of squished pea.