What you should know, and what I found out the hard way, was the many times LFSs mislabel different strains of rasbora as Harlequins. You'll often find Espei or Gold Rasboras labeled as Harlequin when in reality they are not.
Harlequins have a bright, rusty red color to them when the mature. I've actually found it difficult to get a hold of TRUE Harlequin Rasboras in my area. It seems that LFSs are always selling either Gold or Espei rasboras, not true Harlequins.
I kept them as a kid... Considering them again for my next tank- not 100% sure.
My tanks were always about 77F- they seemed a very hardy fish. School well- like company of their own kind... don't grow very big- never bothered the other fish... Quite peacefull...
Ummm... they don't like being eaten or harrassed by larger fish- had chinese algae eaters (I think that's what they were) harrass mine to death.
Mine never bred- but I never really tried.
They stuck to the top of the aquarium. Not as active as Danios- but still moderately active. Would eat whatever I gave them.
The black triangle on Espeis are thinner, and they have a vibrant orange color to them as opposed to the thicker triangle and rust red color on true Harlequins.