I had 4 dats in one tank (this one being the biggest) and all of them were unstable. I moved this guy into a 170 gallon with no other dats and no really good hiding spots and he turned stable shortly after the move. However, as soon as I tried to put my other larger dat in with him, he turned brown and was very territorial towards the other dat. As soon as I moved the other dat back, he turned stable again.