Does anybody know what this shark is eating?
The fish in this image is Helicolenus dactylopterus. Shown below;



This fish, is more formally known as a Blackbelly Rose-Fish. This fish, is one of the Goblin Sharks' many prey in the deep sea. 

In the photo you posted it looks as if the Goblin shark effortlessly and oddly so caught the fish - it did. This is due to how it consumes most of its prey:


  When they approach it their jaw goes out similar to how a human can stick out its tongue. Then with a sucking motion they draw they prey into their mouth where very powerful teeth are waiting to consume it.


Goblin sharks are quite terrifying...