Rarer ones I would say, at least from personal experience is doubletails, neeeevver seen one myself (would snap up instantly if did)

they problery did have some kind of Fin rot...when i looked at the double tails in the lfs they didnt look like they had fin rot or anything like that but i didnt pay attention to if they were equal. partly because they were on a shelf a foot above my head...not hard to do seeing as im just under 5 foot tall![]()
i brought 4Swordtails once Witch all looked in great health etc.ill have to take a better look next time i go there....they all had crystal clear water and good colors, seemed to be taking ok care of them aside for the fact they are in cupsits so sad to see them in those things.
should'nt do if he's in a well planted aquarium etc.thats awful! hopefully that wont happen to me when i get my betta!