We went and rescued the remaining fry this morning. They are now in a small tank in my bathroom with a hang on the back filter with a sponge over the end. Temp 25C.
I have finely sieved some flake food as it is all have at the moment.
Will go for a walk up the hill later and see if any of the stock troughs have green water but I suspect not at this time of year. My pond is crystal clear and not a bug in sight, especially tiny ones
The fry seem to be nibbling, or trying to nibble, the bit of food that has now stuck to the sponge.