they shoal to some extent, but not like rummynoses or harlequins, they are a hyphessonbrycon species so spend a lot of time low down in the tank, weaving through plants and dancing with their own species.
i found them not to be the least bit aggresive with eachother, but the only thing i could ever keep them with successfully was tiger barbs, anything else ended having to be rescued with bitten up caudal fins. they ignore otos and corydoras (havent tried pygmy corys with them though)
they are a lovely fish but i would say keep them species only or with just otos i wouldnt risk them with shrimp.