Thanks so much for your help, but whatever he had got the better of him and he died last night. Sadly we were unable to keep him alive long enough to discover what was really wrong. We tried the antibiotics which are usually given to poultry, and which on the rare occasions we have needed to use them, have worked. Anyway, I suppose the up side is that we have now wormed all the poultry, although I'm not sure they needed it, they will probably benefit from it. I would like to find out more about the mystery thing which was killing muscovys, but we couldn't find anything on line, except that they very rarely get ill. We've found this to be true over the last 40 years or so - our last one was in his 20s when he died. Although he was only a duck, he was part of our mix and a great character, we shall miss him. I will put some recent pics of him with our hens on our f/b pages later. Thanks again.