Much of the season's stories are set in the Amazon, hence the piranha and candiru. Toothy piranha — you already know about them. The candiru? You don't want to. The tiny, eel-like creature has been known for very unpleasant infiltrations into humans.
Unlike many "River Monsters" episodes, where the fisherman Wade hunts for creepy creatures, Sunday's story about the Sobra Santos is a mystery.
The overcrowded ship sank at a particularly inopportune time and location. It was pitch- black, and the ship wrecked in an eddy near a fish processing plant that attracted a hungry and vicious type of catfish. Some 200 people were killed, and many body parts of victims were missing. The catfish are known to feed on human remains, and the question is whether some of the victims were attacked while they were still alive, Wade said.
"We will never know for sure," he said. "What we're looking into is all the possibilities, what could have happened to all of the people."
The ship was salvaged, renamed and put back on the water. Wade found out, much to his unpleasant surprise, that years later he sailed the Amazon on the same ship.
The British Wade was an avid fisherman as a boy and was on the lookout for more adventure. He wrote an article on his six-year search for the arapaima, the largest freshwater fish in South America, that caught the eye of a television producer. He began working for Discovery in England, attracting the attention of Animal Planet. A special Wade did for Animal Planet attracted so much attention, it was expanded into the series.
"River Monsters" has been growing in viewership every season, the Nielsen company said.
About half the viewers are people who fish, Wade said. Many are attracted to the idea of seeing creatures they have never even heard of. Many of the fish, because they are from fresh water, are particularly ugly, he said.
Wade, when he catches the object of a show's search, always releases it back to the wild.
He urges people who are near some of the waters featured on "River Monsters" not to be frightened, but to be aware of what fish might be near them and understand their behavior.
"One thing that concerns me slightly is that it does give the wrong impression, that everywhere you go there are huge fish that will bite your leg off," Wade said. "In fact, you have to look for them."
And, usually, it's human behavior that causes the trouble. Don't stick your toe in water where there's a good likelihood you'll find piranha.
With "River Monsters" stretching on, Wade is feeling the challenge to find new stories. Like with the shipwreck story, it sometimes means stretching beyond the show's traditional topics. One creature he will hunt for in the Amazon region this season doesn't live in a river.
"Every year we worry about running out," he said.