Imo, that is overstocked. Drop the Oscars. Congo Tetras like flow, like duanes said. If you want a flowing tank, simpling place a HOB on the side, or powerhead. If I were you, I would make a solely Congo River Basin.
2 dels
4 Leopard Ctenopama
a pair of Bullhead Cichlids
2 Lamprologus congoensis
6 African Butterfly Fish
12 Congo Tetras
I like this stock a lot. Congo Tetras are actually quite fun. They get super colorful, and their fins grow long and flowing over their back. When mine are super hungry, they will eat out of my hands.