Can anyone ID this monster ?

It makes it's appearance at time 22:18 it is begging for food with the arapima's it's the large black fish with what looks to me to be a knife fish body but being longer then the arapim's it's kept with. can anyone tell me what this is ?


[video=youtube;HueSXkokJQM]https://www.youtube.com/watch?v=HueSXkokJQM[/video]

yeah your right the quick moving video blurrs it's body thank you