Ahh, I got ya. Well, strangely enough we used to have Mertens' Water Monitor on exhibit and by the looks at one of the pictures, that may be what is pictured. I'll look into the switch when I return on Sunday and let you all know.
The Merten's Water Monitors are on exhibit. Two in the freshwater crocodile exhibit and two in the monitor exhibit. They have two spiny tailed monitors in backup.
There is no Olive python on exhibit. (I could not find out if one is in back up or at Fell's Point or not).
Emperor Gudgeons are on exhibit.
I think that was all that was confusing.