Are the walls of the tank painted by chance?? My figure 8 was glass surfing really bad at first, but after I painted the back (and sides) of the tank black he calmed right down. Idk if seeing out all around him was stressing him out. It limits me because I can only see him from the front glass, but he's so much more relaxed now that it was worth it. I also reduced the brightness of the light...... Side note: I've noticed that for the Anubis to do well in brackish, the light has to be kept at a higher intensity. I'm not sure why yet tho. It's just my observation. But the difference is VERY noticable.
Hope this helps!!!