Well, i haven't seen the RTBS try to suck on other fish yet. If i do see it or suspect it i will separate them.
Yes, my shovelnose is a Sorubim lima. The tiger shovelnose (although very pretty) is too big and mean for my tank (it'd probably bust my tank open). One of those fish that i would not recommend buying.
I'm really fond of the RTBS, so hopefully he grows fast. BTW, my RTBS seems to be a very finicky eater. He only eats one or two bloodworms at a time, doesn't eat tropical fish flakes, eats shrimp pellets (only the small pieces floating around) and doesn't really bother with anything else (worms, veggies, algae wafers).