Stable referres to the black bars on any datnoid. If you have a stable bar datnoid tha means the bars are dark black. Unstable is in refference to a datnoid thats bars are fadded or darker in some areas then others, sometimes they appear non-existant. Many stable dats become unstable if they are scared, water conditions are poor, or if the lights go out for a long period of time, and they begin to rest. some ppl have dats taht are just stable all the time. Some other ppl will have dats that are unstable all the time no matter how good the conditions are.