What Kind Of Fish Are These?

So, we were at the Heidelberg zoo the other day and I happened to take a video of some fish. 

But, I was puzzled as to what kind of fish they were.  They were big and rather strange looking. 

You would think big fish would want a deep place to go, but they seemed to enjoy hanging out near the surface of the water. 

They were interesting looking.  If you know what kind of fish they are, please let me know. 

Here is a link to the video:   http://youtu.be/M1nayrTcx_w