Pufferfish not eating, looking emaciated

[Hannahhhh]

I got my blue spot puffer a month or so ago. It’s never been a good eater, to the point that I was pretty worried about him at first. But he seemed fine, so I figured he was getting enough food from the tank. Today I found him resting on s rock looking not great. I gave him a nudge, and he swam away to rest on another rock. I was finally able to get a good look at him, and he’s so skinny. 

I don’t know what to do for him. I’ve been trying lots of types of food but no luck. 

 

I put him in a breeder box tonight to try giving him better access to food, but it seems to be stressing him out even more. 

 

Does anyone one have any thoughts? I feel so bad for him. 

[Ratvan]

Can you get a photo of its beak? What foods have you tried and did it show any response to any of them? I know its not the same but I had Pea Puffers that i had to trim back the beaks of (nightmare)before they could eat. Also when you attempt to feed do you try a single food at a time or a mixture?