Koi for home and garden, Glen Takeshita, 1969, revised 1982.
This book provides an interesting look at the past beliefs about koi. The opening remarks about history is likely to confuse todays koi keeper since he talks of hundreds of years of koi breeding. However what he is referring to is the breeding of common Carp for food, not the colorful Nishikigoi we know today.
The ideas of pond building have certainly changed. At the time of this writing it was believed ponds as shallow as 2.5 feet were adequate since there was little oxygen in deeper ponds. It does touch on the need for filtration, water changes, and medications for diseases and infections. Parasites are not covered. Food was mostly hand made or was at least standard fish food supplemented with additional live food and vegetables.
The 1982 edition of the book is filled with colorful images of koi any of us today would be glad to have. There is even an image of the First All Japan Show winner. This book is more of a collectors item than a modern reference on keeping koi. It can be found fairly cheaply on Amazon.
LINK: Koi for Home and Garden ISBN0-87666-54-x