No, he means that when they are black they are happy. When they colour up and show off their bars is when they are stressed or flexing their muscles... However for the longest time most of my dats were dark but still highly active. I just overhauled my tank, rearranged the rocks and driftwood, and added a ton of fake plants, now all my dats are stable and still very active. Also my temp used to be around 84*F or so, but when I redid the tank I lowered the temp to 78*F, so the temp could effect their stability as well.