The pink river dolphin (Inia geoffrensis), is an extremely rare and the largest of freshwater dolphins. It typically lives in large fast flowing areas of the Amazon river, they travel in packs usually of around 4.
This dolphin also has a very distinct mating ritual.It finds a rock fit for it’s mate and presents it as a sign of good faith for copulation. Interesting…
Also I drew the most thought of fish when people think of the Amazon, the voracious Piranha
Source: http://llewmejia.tumblr.com