You can put OSCAR & PACU with it
I'd want to see another picture or two, but I believe it is a Paradise Fish.
Paradise Fish, Macropodus opercularis, maintenance and care
It is deffinatly a male Betta.
Thanks guys, I looked through a couple off books I have, but could not come to a conclusion. My Sister said the fish is four years old, but could not remember what it was. It does not bother my Tetras but killed my Corey's in a day.