sommetimes
No, pirahnas are freshwater fish.
Simply, they eat on carcass' flesh, be it humans' or animals' .
parahnas live in fresh water scince the amazon is fresh water and is swarming with parahnas
sharks,whales,parahnas,catfish,and coral
I would say that parahnas are not considered scavengers because they kill their prey with their sharp teeth and are other animals' natural predators. Scavengers are usually depicted as an animal that looks for left overs; things that are already dead or randomly lying around. Because the parahna is equipped to be a predator and rips the flesh from its prey, making an outright attempt to hunt and kill, it is definitely a predator rather than a scavenger.