The Top 5 Largest Freshwater Fish Fish Scientific Name Maximum Length Maximum Weight 1 Wels catfish Silurus glanis 500 cm 306.0 kg 2 Arapaima Arapaima gigas 459 cm 200.0 kg 3 Soldatov's catfish Silurus soldatovi 400 cm 40 kg 4 Kumakuma Brachyplatystoma filamentosum 360 cm 200 kg 5 Alligator gar Atractosteus spatula 306 cm