I think the signage is mostly representative to illustrate species found in NZ waterways. The closest signs are all invertebrates (mostly larvae), which would just be eaten if in the tank. The row of signs at the far end are all fish - there's a reasonable chance all of those were originally kept in the tank, but the only species in there currently (that I saw) were Giant and Banded Kokopu, Koaro, and Redfin Bully. All of them are visible in the photo (the Koaro is the skinny fish at the left, the bully is at the glass about halfway along the closest panel, and the larger fish are kokopu).
