They do get stable depend on the mood. Substrates and other dats or other tankmates will also help it to make it stable. However some will take time. Most small dats, especially IT in most cases, they are unstable at 6" or smaller. The older they get and the more they get used to the tank the more stable they become.
This is how I got mine stable. Your datnoid is not conscidered "stable" until it is always nice and gold. A stable datnoid should not change colour even if it's enviroment is being changed, ie: during a water change. Some say that a datnoid doesn't become stable because of it tank set-up. Some say that if you have lots of places for the dat to hide it will take a very long time for it to become stable or it might never become stable. People say that if you put the datnoid in a tank that has no decor and is bare bottom, I personally don't know why they say this will help but it WORKS! I put my guy in a tank like this for a little while with no other fish and just like that over a period of time he became stable. Then when I put him back into the main tank he never went unstable again. Others feel that if unstableness can be caused by tank mates. If your dat is being pushed around by other it will most likely not be stable. OR some say that if your tank is crowded with fish the tank might not be happy OR it could also make the dat stable because the more fish the less territory conflics and therefore less aggresstion. But if I were you I would just feed it very well and put the datnoid into a bare tank by itself...it will most likely become stable. If not luck then further your mission to help get your datnoid stable by trying other ideas.