I dont think Ill be keeping the harlequins to max size (2") - they're only about 1" now.
Squawkbert - are you thinking of badis badis? The scarlet badis actually doesn't get larger than 1 inch.
http://www.fishforums.com/forum/profile-article-discussions/13510-scarlet-badis-dario-dario.html
You're right (I was looking too) - I confused Dario dario w/ Scarlet badis. Darios are larger. No aggression problems - provided adequate space (in a 10g, I still thnk a pair is enough).
Also, I agree that Harlequins seldom reach 2" (mine are *maybe* 1.3") and I further agree that the 1" per gallon rule is junk given the potential mass differences between torpedo and bathtub shaped fish of the same length and the bioload differences between predators and herbivores.