They love rocks and wood to chill on... At least, that what they did at my place. I had three of them in a large tank. And they also like to hide in those plants I had. Don't keep too friendly fish with them. But they're beautiful, aggressive and interesting fish to keep. My gf just didn't like them too much. So, at some point they moved to a large tank at my friend's place. He kept them with a school of butterfish. He got rid of those butterfish when they aged because they needed brackish water instead of fresh.