Some good news.
On closing up the chickens last night, one of the children decided to use the torch he'd taken with him to scan the pond, and there 'sleeping' calmly at the bottom of the pond were three (of our original six) goldfish.
It seems at least half of them survived the onslaught earlier this week.
Today they were nowhere to be seen again, even when food was sprinkled on the pond. We think they are still in mortal fear of being seen by a heron; but at least some of them live on!
Dum vita est, spes est.