Records of diseases of grey mullets in culture facilities are relatively scarce. Paperna (1975) described a number of parasites and disease conditions occurring in open waters, some of them causing serious fish kills. Fish farms are generally stocked with fry and fingerlings collected from such waters, and so there is every likelihood of these infestations being transmitted to the farms. Heavy infestations of Ergasiluslizae in M. cephalus have been observed tocause serious losses in brackish-water ponds on the Mediterranean coast of Israel. The crustacean parasite Pseudocaligus apodus is believed to infect M. cephalus, and M. capito is infected by Caligus pagete in fish ponds, causing mortality. In fresh-water ponds, Saprolegnia infections have been found to cause serious mortalities.