Gobrian44:
I don't know much about RTC's but I think you might look at it like I did, when I had my Oscars.
When my Oscar's were the size of which your RTC is now, they were a curious lot when they had foreign objects put into their tank (e.g. hands and fingers). You might try as I did, when they are young, to put your hand in half the depth of your tank, holding a large piece of food say maybe 1 to 1-1/2 inches square. I had to do this twice as they are voracious eaters. Get your RTC use to the presence of your hand being in the tank. Eventually it will become accustomed to associating food with the presence of your hand. As they became larger I was able to have them still eating food held just under the surface. Once in a while, They would eat out of open palm. I know that RTC's have barbels (whiskers if you will) and do not know the sole purpose of them are for, other than to be a type of sensory device for them. If they used them as a weapon of sorts, I have no idea. But they can appear to be intimidating as they become larger. Of photgraphs that I have seen, they are intimidating to me. But that is about as far as I am able to help you with, if at all. If you know of any member who may own or has owned one, send them a PM and see what they say.
Later on when my 2 Oscars got to be about 7-8 inches in size, I also trained them to play volley ball between two tanks sitting side by side. I did this under supervision, so they would not jump from one tank to the other unsupervised. But that's another chapter to be read.
I hope I have been helpful. I wish you much success with your RTC.
Until next time . . .