The ones I have seen were bitting at the glass to get at my hand. Its funny the few full grown red tails I have seen were friendly or should I say tolerant of tank mates and me. I group jards and leiichardtis together, they tend to be the worst but I have also seen some that were reasonably good natured.
I guess I still need to spend more time with the different speices to fully appreiciate their different personalities.
I have to say that although ours jumps out of the 125gal we have on occasion he's so fast that he jumps up out of the water to tries and grab a large feeder from your hand...thats a pain when your just doing something to the tank and he mistakes you fingers for a fish!
His fav is x-large goldfish feeders and cod fillet cut up