Definitely a beauty ! More than enough visual blocks and hides. Then it comes back to what Max said about heirachy being more than likely the main cause. I ve never kept Cobues so I have no idea of sexxing males and females and have never needed to vent any to find out as all my fish have easy tells as to sex other than my polys which aren’t fully grown yet either way. But if he isn’t tattered and torn and stressed out then you have no real problem and he’s simply on the low end of the stick. I had an Aulonocara juvenile that I swore was a female as it was extremely dark and no one bothered it. I placed it in a 65 gal with 2 juvenile male sulfur heads and within 3 weeks it went from dark to displaying an electric blue beard and body as well as it started to act like a male and began chasing the sulfur heads. So he was dulling himself to avoid being picked on by my full grown red shoulder. Here is a photo of him now. He has been replaced back in my 125 with the adults and he is still holding some of his coloration as I ve only just placed him back in 2 days ago. So if you are able to seperate him into another tank to reduce stress and allow him to eat well for a decent amount of time without concern then it’s possible you could trick him so to speak into holding a brighter coloration even when placed back into the big tank.
