Sorry to comment on another old media post, I’m just going through all the media labeled C. limbatus looking to see who has exhibited them. But this one I think may be a very real treat! I don’t think it’s actually a proper limbatus at all, but rather an Australian blacktip shark (C. tilstoni). Aussie blacktips look extremely similar to their cousins, but have a lower vertebral count and different genetic markers. Typically that would mean they can’t be visually distinguished, but they also occasionally feature black tips on their anal fins. C. limbatus almost never have them, while spinner sharks do. This specimen however doesn’t have any of the other typical spinner features such as a more robust and less pointed dorsal fin, and it’s also set further forward on the body rather than behind the pectorals. I think you’ve observed an extreme rarity here, a shark that can likely be ID’d as a recently genetically distinguished species. There’s what I would call a small chance that it’s a limbatus with an anal tip, which would be quite a rare sight too.
Here’s the Wikipedia image from the species’ description paper that has a black tip on the anal fin.
