Studies on digenetic trematodes of some red sea fish 1. General survey

Abstract

812 Red Sea fish, belonging to 33 species, were examined for digenetic trematodes. All species of fish were infected with one or more genera of trematodes. Out of 812 fish, 394 (48.5%) were positive. The incidence of infection varied greatly in different fish families, being lowest (5.0%) in Gerridae and highest (100%) in Platacidae and Priacanthidae. Sex differences in the incidence of infections were considered in various fish families. Six species of fish harboured one genus of trematodes, 4 species of fish had two genera while 6 species had three genera of trematodes each. The other 17 species of fish were infected with 4-14 genera of trematodes each. Host specificity at the generic level was considered; most trematode genera were found in 1-4 species of fish while some parasite genera had a wider host spectrum, being found in 5-15 species of fish. The incidence of trematode genera was correlated with the intensity of infections in various fish hosts.