in the words of terry clarke "be a man, get a jag" 
she's an interesting jag too. very placid, makes friends with little fish, gains their trust, can be tank buddies for ages, till one day she will suddenly turn on them and eat them, usually spitting them out once they stop wiggling.  
aside from live food, i have never seen her eat anything else. she does it behind my back. i know she eats, her belly is always full when i come back. i put food in, massivore, shrimp, etc etc and she just guards it until i have left the room. once i tried spying on her from behind my bed but i'm pretty sure she saw me because she didn't eat at all, she let the tinfoil barbs pig out on it. even if i don't feed her for a few days, she still won't eat in front of me, but if i leave the room for a few minutes, it's gone when i get back and she's looking fat.  
i have a flatmate who also refuses to eat in front of people. when we get dinner at the mall we have to take it all the way home to eat it, he won't eat at the mall.  
what's up with all these eating disorders.