Saprolegniosis (Chapter 29) is a widespread, familiar disease (or a complex of diseases, perhaps) seemingly accorded only a lowly place in the economics of fisheries. Save for occasional outbreaks, it is a malady of endemic proportions with which the freshwater fisheries industries coexist. Not so the crayfish plague (Krebspest, Kräftpesten), caused by Aphanomyces astaci (Schikora, 1906). This ...