I have a 75 gallon tank with one pair of angelfish, 9 congo tetra, 4 bolivian rams and one probably stunted common pleco. He's apparently 5-6 years old and about 6-7 inches, so not huge. I am thinking of adding a single severum. Could this work? I read on the internet some say yes and others say no. I would start with a small one in hopes that it would grow used to my fish.