They might be breeding (black skirts)?
I've had the black skirts, eight of them, for several months now. And I think they've reach breeding age, because I have been seeing some strange behaviors out of them lately. Tank params are 79F, pH 8, moderately soft water (general hardness is high, but pretty low carbonate hardness), amm0, trite0, trate between 5 - 10. I do WCs at least twice a week of roughly 30-40% each time.
Here's a summary, please tell me if this sounds like breeding, or if I have another problem in this tank:
1. Big difference in size between males and females...think it's split 4 and 4
2. Increased nipping amongst each other
3. Males are doing weird "dances" sometimes, swimming sideways and bending sideways too, with crazy flapping of fins. Seriously, I thought they were having seizures.
4. Females are fat (and sassy), and it's not due to overfeeding
So, your thoughts? I think breeding(obviously), but I'm really good at being wrong, so I need some help. Are my nippy babies grown up?
1 - 55 gallon planted community
3 - 10 to 20 gallon planted betta tanks
My advice: slow down, think, and be willing to learn. Then you'll be fine, no matter what.