The Duke of Westminster probably still owns more land, in terms of monetary value per square metre, than any other individual in the UK and much of this is in the wealthier parts of London, he also owns a large Estate on the banks of the River Dee near Chester. I was called there in the late 1980’s to give advice on a problem that ‘they were currently experiencing with their fish’.
On arrival, a member of staff took me to see a landscaped area of the gardens that held many beautiful circular, ornamental ponds built in concrete. They were around four metres in diameter and only shallow in depth and had a fountain in the centres, they must have been well over a hundred years old and true craftsmen had carved the stonework.
The ponds contained thousands of extremely large Golden Orfe, on size alone these were easily worth £200.00 each to garden pond keepers. It must have taken decades to get them to such a size. My guide pointed to them and then pointed out to me the ‘thousands of grey, circular things crawling all over their bodies’. I had seen many normal levels of argulus infestation before but this went to almost epizootic proportions with the sight before me on that day – in short, they were heaving!
Their bodies were literally crawling with this parasite as I inspected pond after pond of Golden Orfe. I advised my guide that I could easily eradicate these parasites if they were present on Koi by using Masoten Powder after first calculating the water volumes of each pond. Alas, Masoten is an organophosphate and Golden Orfe are a part of the salmonid family of fish unlike carp of the cyprinid family. This remedy instantly affects the central nervous system of the Orfe and causes their spine to bend permanently even after an instant of contact. I have yet to come across any other medication that will successfully eradicate argulus other than Masoten, which has long since been a ‘banned substance’ for use in fish ponds.
The only suggestion I could offer to resolve the problem was to take portable ponds to the grounds, fill them with water and add good supplementary aeration. Then each fish would have to be inspected under anaesthetic and all the parasites removed individually by tweezers before being placed into the temporary ponds. After this, the water in the fish-less concrete ponds would require a triple dose of Masoten in order to destroy any un-hatched eggs present on the surfaces of the ponds before emptying these ponds to waste after a few days. Two weeks later the process would be reversed, the concrete ponds would be re-filled and the fish would once again be anaesthetised to check that no un-hatched eggs retained in the mucus had hatched and were visible. After this, they could be returned to the concrete ponds free from argulus.
It was only after I outlined my suggestion that my guide mentioned, for the first time, that they now had an unlimited supply of free water from the River Dee nearby. When I asked for more details he mentioned that The Duke had hired a ‘new broom’ to initiate some cost-cutting exercises on the estate, one of which was to economise on the mains water usage. He then took me down to the riverside to show me a huge pumping station that had been installed next to the banking some six moths earlier.
Something must have then registered inside him when he said – ‘Oh, come to think of it, the problem with the fish only started a few weeks after we topped the ponds up weekly with river water!’
My estimate for carrying out all the work was instantly rejected by the ever-thrifty Duke although my visit costs were paid in full without question. I later learned that all the Golden Orfe had been illegally released into the river and the ponds emptied and steam cleaned after which they were allowed to dry for a week or so before they were re-filled and new stocks of 3” Golden Orfe were introduced.