It is hard to tell. The picture from below the head is a bit out of focus, so I couldn´t really count the number of pores to see wether or not it is Hoplias australis. It is definately not Hoplias curupira, as a specimen of curupira would have multiple mini-pores on the dentary by that size, rather than well defined and single pores. Still, I am not sure if that is a Hoplias australis. It could also be Hoplias brasiliensis, by the colour pattern in the second, lateral picture. I have the impression that H. australis is somewhat goldish, but it could be lighting in the tank throwing off this artifact.