Presumably there is a barrier or stand-off wall/fence to stop visitors getting to the edge? It's just not in the photo because Devil Fish is standing next to it.
I think they're pretty hard to get past here, with wire on three levels of the fence. Not impossible, but visitors would have to make a very active effort to cross the barriers, and it's not easy for children to run straight through them. The fact that the visitors will have just walked past the leopard enclosure and round the side of this one might make them a bit more cautious than usual (especially with their kids).
Attached is a photo of another part of the enclosure showing a bit of the barrier.