it looks like the two or three "rectangles" in the wall are covering where small tanks will be (for the rainbows etc). Although interestingly the sign in front of the main aquarium there has pictures for Murray cod, (what looks like) Boesman's rainbow, Australian lungfish and what could be a Scleropages. A very odd mix indeed!
The Murray zone never quite worked out and will be scrapped completely. This area will re-open in June after renovation as an extension of the Ganges zone.
@DavidBrown: The boat ride with views of rhinos, giraffes and elephants is open, it's called the River Safari Cruise. The Amazon boat ride is still the same and won't likely be re-worked any time soon.