Here's what it looks like when the louse replaces a fish's tongue. While other parasites may seem like they could be doing something similar, they don’t quite cross the line into full organ ...

While the nets were empty the underwater floor wasn't, instead it was littered with dead fish that had the life sucked out of them from these parasites.

There is the Banggai cardinal fish, found only in Indonesia, which keeps its eggs and newly hatched babies in its mouth for two weeks. Then, there are gruesome parasites, his latest obsession.