As posted earlier, this is a south american silver arowana. Very common in the aquarium hobby and you can get small ones for as low as $15-$20 a piece. They grow fast and will quickly need more space than people think. Large ones such as the one pictured in the original post are not wanted and generally people have problems finding appropriate homes for them. There are always people trying to unload them either for dirt cheap or sometimes free.
They are not the expensive asian arowanas that you come across that go for thousands.
I hope this clears it up for you fishing89.
I've been keeping fish since I can remember and have had my fair share of expensive asian arowanas.