I've had a pair a keyholes for mo this. They normally are always together. Last weekend I redid their tank and added live plant and switched around their driftwood. Since then I barley see one of them or if I do it's just laying low on the gravel behind rocks or In plants. It also looks like her...
I'm pretty confident I got a pair (I watched them for an hour to make sure they were bonded and wouldn't kill eachotger before I got them) and I've had them for a few months and I just wanted to double check :) tank is cloudy because I redid the tank including adding some new sand