I have 3 turtles in a tank. When I'm giving them food sticks, I use my fingers to make sure they have the right amount. Couple of months ago I've been bitten many many times. I found out the farther away you your fingers the more likely they would bite your fingers. I Think its are just harder for them to aim when they have to stretch their necks longer. So now, what i do is hold the food sticks as close as possible and they can aim more accurately. And now they know when they bit my fingers because they would let go immediately and go for the food stick again. I remember when Samson, about 2 months ago when he is about 3" he bit my fingers and it bled. He has a very sharp beak. now he is 4" I can put my fingers in front of him, well he would bit it but not that hard. He would release my fingers as soon as he realize its not food.

But it is another story for Bunsoy. She is 3" now. I let her bite my finger. The initial force of bite was really gentle. Its just like she is holding onto my finger so i didn't move it, I thought she would let go. After a few seconds she did put pressure to the bite and tried taking tried taking it to the water. So i wiggled my fingers and she let it go. Well, I think their manner of bitting depends on their personality. But atleast they have change. Before they would strike my fingers at full force. So when they missed the food sticks it would hurt. Now they bite genlty

So goodluck with your turt.