Anyone else keeping Denison barbs/roselines ??

[urs4]

I have eight 4-5" roselines and I've noticed a difference between them which might indicate male/female. On two of mine the leading edge of their anal fin has a yellow band running from tip to body. I noticed the other 6 do not have this and some of them are larger than the ones that have it. I also noticed the dominate one per say will swim below the largest one like a ramora on a shark. i.e. keeps pushing his head into her belly as they swim at the same speed


Curious if anyone else can share what they see in their tank.

Thanks,
steve