Definitely a bony-tongue but I think it is more likely to be one of the Saratoga species rather than Silver/Black Arowana simply because they are much easier (and a lot more legal) to acquire, Melbourne Zoo have had several Saratoga’s in the past so it’s likely that they’re attempting again.
@Yoshistar888 Black/Silver Arowana are legal to keep in Australia, it's only Asian Arowana that are illegal. I agree that Saratoga is more likely though.
I don't think this is either of the South American arowanas (Osteoglossum), as the caudal fin shape looks rounded rather than diamond-shaped. I agree that this is one of the two Australian species (Scleropages).
@Osedax they are legal to keep (in some states) but they are not legal to import and there’s no captive breeding of them that I know of in Australia. They definitely do occur around though, I’ve seen them for sale on websites.
@Jambo Which species? Two species are commonly called saratoga, Scleropages jardinii (Northern or Gulf Saratoga) and S. leichardti (Southern Saratoga). Both are present in Australian zoos and aquaria, and can both be readily obtained in the Australian pet market too.