Green spotted puffer turning black when eating

[Peacock78]

So I have a green spotted puffer in a 55 gallon cycled brackish aquarium feed him a mixture of blood worms mysis shrimp krill snails crabs and market shrimp but every time he eats he looses his colour and turns black then about one hour later he turns back to normal

 

[Capt_Rick_Dixie]

Sounds to me like he's just getting hyped on his food. Mine does it every now and then. Does he do the same thing while eating other foods? Regardless I wouldn't worry too much unless you're seeing any behavioral changes outside of feeding time.