Of course shouldn't everyone? That's his and that's his. If Brick weren't so tough do you think he would try to go for Brick's place as well? Put it closer to Rex's haunts. Would it make a difference? Get an extra one? I remember a cichlid rule that I followed. More shelters/caves than fish. If one claims another's territory, there is always someplace to go. Severums are cichlids too, but I don't know if their breed likes caves. I will check on that.
I have a feeling a third pot would give Boss a third option, lol. Rex seems to only prefer the pot on Boss' side...he never bothered with the other one. So for now, Boss has two apartments. He goes back and forth daily.
Its pretty funny Brick will go over and see if Boss is in the original pot but isn't. He doesn't seem to care about the pot right on the edge of his territory where Boss hangs out! Cichlids are kooky.
When the lights are in dusk and night mode, no one seems to care about territory at all. Last night Chip was sleeping with Brick in his favorite spot??? Boss roams the tank, drifting along the current. Rex disappears in the 'jungle'. Brick dozes off under the pothos, his fav location. The "no territory at nigh" rule was in play even with just Boss and Brick in the tank. They would sleep on each other's side.
I actually had the pot on Brick's side where Rex hangs out mostly. He never went near the pot, go figure. Boss checked it out...so I just edged it over to 'neutral' territory. Boss claimed it. So Rex seems happy to go 'freestyle' and sleep under plants. He still doesn't go to Boss' side too much, just sometimes. Chip is allowed to stay on Boss' side now as long as he isn't near the pot. So he's in the grove or the open area behind Boss.
Nobody goes in Boss' original pot, not even Brick (unless they fight and he gets forced into it).
But the great thing is everyone is really getting along pretty well now. Everyone eats like greedy pigs and no one is shy.