Dominant Harlequin rasbora?

I recently got a male betta and four Harlequin rasboras for my newly cyced tank (getting 4 more in a week, don't worry ). The rasbora and betta get on fantastically, but as I was observing my fish I noticed one of my Harley's was chasing the others, flaring and then going off by himself. From what I read I think he's male and the other three are female. He's easy to tell apart as he's smaller and a lot more colorful. But anyway, my question is - is it normal for Harlequin rasboras to do this? Maybe I just need a bigger school? Thanks!

 

He is probably just either establishing a nipping order or trying to spawn, my males that all of the time! Can you post a video? Also do you have any live plants? Mine live to spawn on anubias.

 

I personally find that to be very odd behavior for harlequins...I have had a school of them for years...they are, in my opinion, one of the most peaceful, laid back, schooling fish. I have never seen any aggression whatsoever...Even when I only had 3 of them (before I knew better)

Your profile says the tank is about 18 gallons, what is footprint of the tank? (lengthxwidth) Do they have plenty of swimming space? I worry that a group of 9 of them with your betta is getting cramped for a tank that size. Right now you only have 4 though....maybe upping the school will help with aggression, but the tank size worries me. But again, the aggressive behavior surprises me with harlequin rasboras.

 

Once you add more to the school, it should get better.

Hope you have a backup tank for the betta.

 

They should have a minimum school of 6. However they do sometimes chase each other around but do not hurt each other or bother anyone else. Alison

 

I do have some live plants, the length and with of the tank is 24 x 12 inches, I think they do have enough swimming space and look quite happy. He's not doing it as much today, I find it funny the way he likes to go off and explore by himself though, they have so much personality! Haha.