I have 2 roselines they got along well with each but for the past few days I was seeing that these two were moving quickly close to each other like circling each is this a territorial display or breeding
I just recently added 6 Roseline sharks (Denison Barbs) to my tank. So, I'm by no means an expert. However, when I researched them it appears they prefer to be in schools of at least 6... the more the better. like most barbs there is a hierarchy that will be established and tested. With only two fish they are probably hyper-focused on each other. It doesn't sound like they are being too aggressive towards each other, so I wouldn't be too concerned. It's most likely them establishing dominance or the weaker one felt confident enough to challenge for dominance. How big is your tank? Are there other fish in the tank? Do you have room to get more Roselines?
Well I have a 30 gallon which I know its small fr them but stocking wise.not much fish 2 dwarf neon rainbows and some black skirttetra which are extremely peaceful and a female betta btw I feed them asap when I turn the lights later they don't show the territorial aggression also I do not plan on getting more as I know tank is small but also these are fish which are getting extinct so it makes me feel bad otherwise tank conditions are all good regular weekly waterchanges