We only had them once, and the tadpoles, which in the NZ variety are very big, lasted until the goldfish realised that they were edible.
I take most of the weed out of the pond in Spring, otherwise I get lots and lots of little goldfish. It worked for tadpoles too, which was an unfortunate result, as habitat loss is making the frogs rarer, but if you don't have fish, you get Mosquitos.

I still remember the dreadful screams when a cat caught a frog, which usually startled the cat long enough for the frog to make a getaway.

When the first male frog found the pond, my neighbour drove around the district looking for the "Bastard who was revving a Go-Cart at that time of night." Not so silly, they do sound very like a few revs of a two-stoke engine.