Here's an idea: use a small GLASS bowl to put the fish in. Like maybe a Pyrex dish. That way, the little snaky can see the fish in there, and will be tempted to snag them. That was how I got Green Girl to eat a few years ago: put minnows in a shallow Pyrex dish.

The big pool would be great for basking and swimming, though.

Also, about the hide: make sure there are no African swallows around. And medieval English knights. They like to carry coconuts.