My ST try to bite my arm while doing WC. It did not hurt but the ST's jaw seem to hurt a little. He then tried to stretched his mouth a couple of times after that. I would not encourage hand feed as i know some ppl lost their Dat due to it trying to jump up for food and accidentally hit the top glass of the tank and injured itself. One of the guy i know lost a 20" ST because of it hitting its head against the top glass.
I also got bite by my 20" aro. feel like got pinched by a strong paper clip then yeah, alot of teeth marks and blood start to shoot out.