Must say this is only a recent discovery of mine as well! Hudson now gets tuna, sardines or mackeral several times a week. Don't go for Sainsbury's basics range - it's all in brine which is a shame as tins are so cheap.
A few months ago he developed a dry, bald patch on an elbow and since swimming in the sea and having fish regularly it's now just a slight bald patch - the skin is lovely and soft. All I need now is to remember to apply some Megatek shampoo to help the hair grow back.