ive kept shoals for alittle over 10 years, and broke down my last shoal tank 3 years ago, just didnt want the hassel of a 530-720liters tank anymore, but couldnt "live" without a tank, and being from denmark its close to impossible to get serras, so read and artical that pygos are basicly not a "real" school fish, so i got a single pygo, and i have _never_ had a more aggressive fish, finger chaser, follows me around the room. he is not skittish at all, i dont want him to hurt himself trying to chase the tetras and ram the glass, i just wanted more life in the tank with acouple of tetras
this is all just my experience