Hi,
I see you know your zoos!
They were housed in a 77,000 gallon "river" within a 1/2 acre exhibit. We were able to warm the water as needed. Unfortunately, there was no way to heat the air in their exhibit without super-hearing the entire public area as well. In the old days, this would have been done - steamy reptile houses were typical. But management felt that today's visitors would not be so accepting of this. They grew well for 14-15 yrs, then began having health problems that were linked in part to poorly functioning immune systems; inappropriate temps long term seemed implicated. There were some losses, and the decision was made to transfer the survivors to institutions where they could be housed outdoors, or heated properly indoors.
Sorry, I should have been clearer - Rhom Whittaker (whom I've had the pleasure of snake hunting!) did supply us with the animals, from Madras. Their ancestors originated in Pakistan, as I recall.
Best, Frank