Arulius are a highly likeable species. They are, however, not small fish - they grow in short term to 100mm+. The markings tend to fade with age, but the finnage extends proportionately. Best kept in a group of 4-6 individuals, (female heavy group), which leads to suitability issues.
I've had them, very nice looking fish once they've grown a bit. I'd imagine they'd be fine with your other barbs as long as you have a few of them. Mine got on fine with all my fish apart from my silver shark, no idea why, they just used to permanently chase it.