i have 3 male cons (4.25, 4.5, and 5) all in a 55 and they all had small nuchal humps going from biggest being te most dominant to smallest the most submissive. I removed the oscar, and immmediatly the biggest con was kind of the tank and his hump grew
I have two marble con males (a 4.5" and his son, 2") who are in a 30gal long and neither have any nuchal hump. Amazingly, they get along perfectly for such a small tank.
The only time my larger one got a nuchal hump was when he spawned with his mate, and even then it was a small hump.
