Guideline River Monsters Season 2 Episode 6 : Rift Valley Killer

Jeremy Wade is on a quest to Africa's Rift Valley to explore the roots of fishing and the monsters these first fishermen faced. It's a dangerous place, filled with killer crocs, hippos and warring gangs, but at its heart is a worthy prize: the Mputa, aka Nile perch, Africa's largest freshwater fish.




NILE PERCH
Lates niloticus

Maximum Length: Up to 6 feet
Maximum Weight: Over 500 pounds

An Invasive Giant: The Nile perch is an important food fish in Africa and a prized catch for sport fishermen, but the species is also a massive environmental nightmare. In fact, the Nile perch is massive in more ways than one. It's a giant among fishes, reaching a length of up to 6 feet and a weight of more than 500 pounds. Anything that big eats a lot, and when misguided humans have introduced the Nile perch into new aquatic ecosystems (most notably, Lake Victoria in East Africa), it has caused catastrophic declines among native fish populations. The Nile perch is now common in the Nile, Chad, Senegal, Volta and Congo river basins, and has been ranked by conservationists as one of the world's 100 worst invasive species.

It's Big and It's Hungry: The Nile perch is silver with a blue tinge and has a distinctive set of big black eyes with bright yellow outer rings. It can live in any freshwater body, but it prefers warm tropical waters. The female Nile perch tends to be bigger than the male, but they're both pretty hefty fish. The species is a versatile predator; a Nile perch will eat insects, crustaceans, mollusks and fish. It gobbles down bigger and bigger prey as it grows in size. When it's not eating, the Nile perch passes the time by making more Nile perch — a lot more. Breeding and spawning peak from March to June, and a female will produce an average of 9 million offspring (most of which don't make it to maturity). The eggs take just 20 hours to hatch. Nile perch reach sexual maturity at about three years of age, and they can live for as long as 16 years.

Jeremy Wade's Tips for Catching Nile Perch: "The main flow of the river was racing from right to left. If a big fish got in this, and I didn't stop it, it would empty my reel and break me off. There was no way to follow it along the bank and it would be madness to jump in the water — not just because of the current, but also because of the crocodiles."