Koi ponds using mesh to protect against herons
I saw a Koi pond recently that was covered in wire mesh - unusually it was at the front of the house, behind a high hedge. I can see they might have concerns about their Koi being stolen but won't it harm the Koi if they brush against the mesh?
Peter Bradshaw, Lincoln
Answer: Ideally the mesh should be at least 10cm above the water, especially if it is galvanised.
I suspect that it was placed there as emergency remedial action against the prospective revisit of a heron. The fish would eventually learn that there is a barrier there and refrain from doing Bottle-nosed dolphin impressions, unless its that time of year they just cant restrain themselves.