Biggest difference I see between him and Columbian sharks is the excessively dark color and lack of white trim to the anal fins. Some of the fins look slightly off shape wise but they also seem a bit damaged.
thanks all, I've just looked at the other forum where I posted similar question, apperently its the SalmonTail Catfish, similar name with Lesser salmon catfish. Here is a link, http://saltwater.aqua-fish.net/?salmon-catfish
cheers