Well...what's "difficult"? My experience with them is limited...although I kept them much longer than aquarists who trumpet success with a species after a few weeks or months...and I just found them too much trouble to maintain my interest them. Shy....but aggressive amongst themselves if crowded. Very demanding of live food, or at least frozen food that is presented in enough current to give it some action...but too much current sends them scurrying under cover. There's always "that one" who is too stupid or shy or too far down the dominance totem pole to get enough food and justs wastes away; there's always food lying on the bottom being ignored and requiring removal. I found myself obsessively counting them several times per day. Okay, great, you're all still alive; are you waiting for me to thank you?
IMHO, they just don't generate nearly enough "utils" of satisfaction per unit of effort required. Your mileage may vary. Remember, many "easy" plants don't survive for me either.
