It's a possible platinum black arowana. It is a black for sure. It has a lot of shine than a regular black. It may turn fully platinum when it is older. I saw one long time ago and it was all platinum white at 3". Either way, it is a nice fish.
It looks like a silver to me with the large barbells (what ever they are called) on the lip. Anyway it's an awesome looking fish! I would buy it and grow it out just to see, who cares what we all think...