Yeah I'd atleast give him something to hide inside or under. A pair of fake Lily pads should work I would think. Atleast then he isn't stuck out in the open and feeling like he's exposed 24/7. Even with a man made hybrid they still have natural instincts and completely open water like that screams danger to a fish. They like having somewhere they can run to to hide from "predators" and if they can't it really stresses them out. In the wild fish have to fear about birds and other animals trying to catch them from the top of the water so even with something that's never been in the wild they still have those instinctive fears of predators coming from above.
But yeah if you want to lessen his stress I would add some caves or a fake plant at the top of the water for him to hide under when he feels threatened. Also, just like many other cichlids, FH's love to dig into the substrate of a tank so if ya could add a thin layer of sand, gravel or small rocks that would atleast give him something to do other then swim back and forth for hours on end. This pic here shows what I did with my FH's tank when I still had him. I gave mine a lil cave to hide in if need be and some sand for him to keep himself occupied. Also showing a mirror to him every day for 15mins at a time should help him get a sense of "dominance" in his tank, it just mimics him chasing off a potential rival for his territory.
Granted all these things I've mentioned are highly controversial in the FH community, most "experts" say to leave em in a bare tank but honestly FH's are just like any other cichlid and should be treated no differently. Give em a place to hide and relax with something to do with his time.
Think of it this way, would you like being in a bare glass box with no chance of escape or anything to do beside walk around or would you atleast want some sort of privacy with atleast some thing to do with your time?
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Still wondering what the problem is...
