i dont no if that is true not sure i asways thought it was the other way around, they are easy to catch when i was younger we used to shoot a bb gun pellet in the water(need bright colour bb) and 20-50 would attack it and then just swipe them up. i let some in my uncles pond with monster koi and they have been doing well the is about 100 there now and tehy breed easy they need a hole and leafs, a good way is to get the bricks with 3 holes in smooth it down abit and stuff acouple of leaf in or make caves out of slate they can kill other males if in a small tank but generally not that bad