One of the best spots in Africa for this prehistoric monster : Okavango Delta Tiger Fly Fishing.
Personnally, I’ve been fishing there during the barbel run, it’s a fantastic fishing adventure.
The Okavango Delta (or Okavango Grassland) in Botswana is a very large outland delta as big as the indian ocean formed where the Okavango River reaches a tectonic trough in the central part of the endorheic basin of the Kalahari. All the water reaching the Delta is ultimately evaporated and transpired, and does not flow into any sea or ocean. Each year approximately 11 cubic kilometres of water spreads over the 6,000-15,000 km² area….
… The Okavango is produced by seasonal flooding. The Okavango River drains the summer (January–February) rainfall from the Angola highlands and the surge flows 1,200 kilometres in approximately one month. The waters then spread over the 250 km by 150 km area of the delta over the next four months (March–June). The high temperature of the delta causes rapid transpiration and evaporation, resulting in a cycle of rising and falling water level that was not fully understood until the early 20th century. The flood peaks between June and August, during Botswana’s dry winter months, when the delta swells to three times its permanent size, attracting animals from kilometres around and creating one of Africa’s greatest concentrations of wildlife.
The delta is very flat, with less than 2 metres variation in height across its 15,000 km²….
More about the Delta on Wikipedia