One of the few TV shows I seldom miss is River Monsters.Jeremy Wade a British biologist and avid sport fisherman tracks down tales of freshwater monsters ranging from the tiny but frightening Candiru of the Amazon to bull sharks which can live in either salt or fresh water. His shows aren't for the easily rattled. Some of these could give one nightmares, for example the Goliath Tiger Fish of the Congo with teeth that make a shark's look modest in comparison. The shows are educational, as when he jumped into a pool full of piranha to demonstrate that they are not the aggressive swarm feeders they have been portrayed to be. But the kinds and sizes of freshwater fish around the world is really astonishing. The goonch, for example, lives in a Himalayan tributary of the Ganges and is said to have devoured people and buffalo. He caught one over 160 lbs. This season's catches include a spotted stingray with a fatal sting and poisonous skin, the longfin eel of New Zealand which has poisonous blood and hunts in packs, killing livestock and allegedly humans, the primitive but dangerous sawfish, electric eels in Brazil and the giant salamander in Japan, said to have killed many children by pulling them under and eating them as at its leisure. It has a mouth capable of devouring itself, being the widest part of its body.
The first link above shows Wade with a 250 lb. grouper, that looks like it could swallow him. That will probably be a some future show.
The only thing that I don't like is that he always throws them back even when they could feed a village. I think if I'd caught some of these fish, I'd have killed them to protect others, or if edible, given them to local natives for food. Others I'd toss back because they're becoming quite rare in the wild.