I take that back. I thought I had a 100 gallon tank, but it turns out to be a 75 gallon. I'm looking to put a 2-inch severum in with a 4-inch clown knife. I will get a 150 gallon in a few months, no later than December. Clown Knives generally grow between 20 and 24 inches in aquariums (unless you have a 300g+). I pretty much have all I need for the fish tank, but I just don't have the time to set it up right now. Keeping in mind that I am going to get a 150 gallon in a couple of months, would a clown knife (growing to 20-24) and golden severum be all I would be able to have or is there space for one more fish like a red scat?