I kinda meant like angels or convicts that will be a pair for a long time for the most part, or jags whre you need a divider unless you want the female killed from harassment, for the most part.
My pair of haitiensus lived together for a number of years very peaceably.
Although before each spawn, they would spar for a while. i believe a lot would depend on tank size, as whether or not they would maintain a peaceful relationship. Mine were never in anything smaller than 150 gal.
She killed a number of males, before she settled on her mate though. Just because you get a male and female, doesn't mean they will pair automatically.