I feel like with this lake, the most interesting thing is the social behavior, which you'll miss out on with singles. At the very least I would avoid anything that enjoys the company of others. No brichardi complex, no cyprichromis, no shellies, no frontosa (kidding, but you never know what the folks at the lfs
are tetlling someone), tropheus, probabbly not xenotilapia, etc.
So what does that leave us with? among the common ones in the hobby, leleupi, julis, calvus, compressiceps
, and more uncommonly, goby cichlid, featherfin, and certainly others both in and not in the hobby at all I'm forgetting. Does that sound like a fun tank? That's probably what it will have to look like going only solos. There may also be some appropriate sized synodontis you could keep solo and certainly smaller ones you could keep in a group too.
I'm considering a leleupi or calvus in my 90g with 2 j. marlieri (not sure if it's a pair, no spawning yet but I had to pull the other 2 julies out when overnight suddenly they just went crazy attacking the other two, when previously all 4 seemed to get along just fine, though this was just a few days ago. they've gotten quite aggressive for the first time with the catfish targeted in a certain cave I can't see into, though at times they do both wander away so I'm not really sure if they've spawned and honestly unfortunately they don't seem to exhibit much in the way of what I'd consider pair behavior, though I'm new to keeping them so I may not be identifying it correctly, fingers crossed though) and 10 cyprochromis and 5 petricola. leleupi is supposed to be a decent solo pick sick they don't care much for their own kind, I just worry about spats with the julis, and have definitely given them more time than is ideal to establish a territory. calvus is supposed to be really tough though so that may be the better pick.