Twurling tangs

[Leko]

My powder blue (6") and whitecheek (4")..
Slowly twirl together and flex thier fins..it's beautiful to watch.

Is this unusual?

 

[Tangdora]

my pbt does the same with both my brown and regal

 

[Peter Houde]

They're threatening each other with their peduncle barbs, trying to establish dominance and territory. It's normal behavior and generally innocuous as long as one doesn't consistently get the upper hand or really beat up the other. After all, boredom isn't good even for a fish. They might more likely be schooling with their conspecifics in the wild, but they'd be having aggressive or evasive interactions all the time in the wild.

 

[Leko]

 

[Leko]

This