I have a pond with a short "stream" feeding it, the pond has goldfish etc.
The strange thing is tadpoles abound (there are a couple of bucketfuls of both frogs and toads) and apart from a grassnake the only predator seems to be Magpies which comb the shallows after tads. these are occasionally supplanted by
jackdaws, crows and even rooks which also have a taste for fry!