Not all bettas are bubble-nest builders (in fact, not all bettas are the long finned fish you see in little tiny bowls at the pet store). I have a trio of Betta macrostoma; they are, like many stream-dwelling bettas, mouthbrooders. Yesterday the female went from having a rounded belly to being quite slim – at the same time, the dominant male’s throat expanded. Keep your fingers crossed – this is attempt #2 for them and I wouldn’t be surprised if it took a couple more attempts for the male to get it right.
Apologies for the poor picture quality. I was trying to just snap a couple quickly; I didn’t want to raise too much of a ruckus.
*
Good Luck with them! I love macrostoma!