Well, A week after my original post, he started eating again. I had to switch to krill and he was able to open his mouth wide enough for that. He was eating great for the past 3 weeks. But a couple of days ago, he came up to eat and went for one of the krill, but it looked like he was not able to open his mouth. He started shaking his head side to side trying to pop his mouth open, but then gave up and went to the corner. I tryied again last night, and the same thing happened. I hope he can pop his mouth open again like last time. Is this normal?