In
Jexnell
’s tank I believe that is a spotted Raphael cat.
Briatlenoses get just large enough to avoid being food, and seem to have this gift where no fish wants to eat them...I’ve heard of them with piranhas.
As for how long until the cichlids become issues is up to species. Oscars pack on an inch or more per month, so that gives you about 8 months before he is gonna start being to bioload heavy on his own.
Jacks and gts grow slower, maybe 1/4-1/2 inch per month (jacks can go faster), but once they hit about 4 inches they begin to get very aggressive.
Severums are slower growers pst 5 inches but the tank being overstocked is really up to how fast the Oscar grows.