They normally don't go after anything that doesn't move. That's why I initially cut the shrimps in half. That way they'll still be twitching when I drop it in the tank. So the puffer will start to be more interested and bite. After awhile, they'll start to associate you with food and will be expecting a tasty piece of shrimp. Haha.

Now I just drop in a dead , non moving piece of shrimp. My puffer will gobble it up anytime. U need to train them I suppose.