First, use your speedboat and travel towards a small rock opposite the dock. The location is near the forgotten village but further south. Location (-163.69,-613.12). Rod Setup: Mokonzi 390 SE Bottom Rod, Fileur 11000 SE Spin Reel, Mono 0.85mm, Sinker 225gram, Fluorocarbon Leader 0.87, Hook #40 with leeches as baits. You can also use Heavychaser 310 Bottom Rod, Ambusher 9000 Sport Spin Reel, Braid 0.27mm, Sinker 200-gram, Titanium Leader 0.28, Hook #40 with leeches as baits. The Mokonzi rod setup is already available together with the Congo DLC that you purchased. If you still want more of them, you can purchase them at shop in the game but at very high levels. Cast your rods toward the aforementioned location during the peak time to catch the fish. You will catch African Bigeye Catfish or Giraffe Catfsh at this spot at times.