Are they mating or playing?

[Xr3]

I'm 90% sure they're mating but I'm not totally sure so I'd love another more expertise opinion. It's funny they were doing this about 10 seconds after I did a water change..

 

[SherLar]

I know absolutely zip about Tiger Barb behavior, but I do know that an abrupt water temp change (as sometimes happens during water changes) can trigger breeding in several fish species. So, if that isn't normal behavior, my guess would be breeding. If they were Cichlids, I'd say they were fighting.

 

[Andy Sager]

The video wasn't long enough for me to see but if one of the fish didn't have a rosey red nose, there's no male so that would be fighting. Water changes can spark spawning in many fish ( as stated above ) but if there aren't fish in breeding mode, water changes are just water changes. These fish might be just fighting for supremacy as Tiger Barb spawning is usually done side by side not face to face.