Originally Posted by
Don in Virginia
When I get a spawn of 150 fry, and begin selling them at 2 inches, there is no possibility of selecting for personality.
Anyway I think that idea is a red herring (sorry, just my opinion). My experience is that when discus are healthy and have little or no stress, they eat well, display well, and their "behavior" will seem good to a human. Of course they will want to breed or establish dominance (they are cichlids, after all), so they may argue among themselves.
Once stress, in the form of over-crowding, poor water quality, or pathogens is introduced into their environment, then they will "behave" badly.
The only way I know to improve their behavior is to reduce their stress. -Don