I had a gold varient Rhom (could of been a brandtii) that I didn't see for almost a year. Literally. It was like having an empty tank. This was about 12 years ago give or take. If I wanted to see the fish I'd have to have all the lights out in the room and actually HIDE under my bed covers! If that fish saw me, it was gone.
All of a sudden, one day I was playing a video game and looked up and he was right out in the open as close as he could get to me, checking me out. Sat there for a few seconds staring at each other and he jolted out of there back to his safe spot. I was floored by that.
Within the next couple of weeks (could of been days) his courage dramatically increased with every day.
Soon, he was in your face the second you walked into the room.