Flooded forest aquarium

The large and dimly lit tank at the far end of the Aquarium (the door to the closed section is on the right). The fishes include several large pirapitinga (Piaractus brachypomus) [which I thought were pacu], various Metynnis, Myleus and Brycon species and the barred Leporinus y-ophorus. All these species are South American.
Note the reflection of the old diagram of the Aquarium on the left hand side.

Having recently visited London for the first time, seeing photos like these make a great window into history. Looks like an engaging aquarium display!

@JVM I think that many of these fishes are now in the large South American exhibit in the Aquarium at Whipsnade.