even though Carribean Manatees are the only Manatees in EAZA Zoos, they could probably add the Amazonian Manatee in such a Pack if it is even kept in any Zoos (still prefer the Carribean Manatee though).The Exhibit Animal could be either Piranhas or Electric Eels (please give us Fish finally).
Then of course the Capybara. I'd also like some Waterfowl. Maybe the Masked Duck. (If they are even kept in any Zoos. They aren't even listed on Zootierliste) They look really nice. This would already give us a nice little Selection of Animals that are living directly in the Amazon River
The surrounding Rainforest could be represented by at least one new Monkey, a two toed Sloth, a Agouti, maybe the Collared Peccari (would also give us a additional American Dessert Animal
)