They do school together but they are also still damsels and can be very aggressive to each other, in the wild or large tanks they have the room to escape or get lost in the numbers, when you stick just 5 or 6 in a 55g aquarium not so much. Some people do get lucky and get a group who dont kill each other but for every story i hear like that you hear 2 or 3 others who weren't so fortunate.
Maybe try 5 line or yellow striped cardinals they'll kind of school together.
Maybe try 5 line or yellow striped cardinals they'll kind of school together.