This is a discussion on playing or fighting? within the Cyprinids and Atherinids forums, part of the Freshwater and Tropical Fish category; -->
What are they doing? fighting or mating?
YouTube - Rosy Barbs Mating?
YouTube - Rosy Barbs Mating?...
Silly me...I just noticed it's in your sig. I was going to suggest getting more as they should be kept in groups of 6 or more but you're 10 gallon tank is already overstocked. The Rosy Barbs can get a pretty good size on them (I've seen them close to 4") and they're active swimmers. A 36" tank length is suggested minimum. The goldfish will also outgrow the 10 gallon. Any plans for a larger tank in your future?