Strange Dennison barb behaviour
We have 3 Dennison Barbs in our tank. Today, two if them were swirling around each other in what seemed to be synchronized movements. Their red and black stripe also faded and fins were a vibrant red. They were very silvery and dancing around like this for several minutes. Afterwards, their colour returned to normal and behaviour as usual. Any idea what this could have been? Some kind of mating ritual? We do not know the genders of them. Any insight would be great.
Attached a photo. The one barb here has returned to regular colour and the one behind is how they both looked during this act.