Observations on Cyathocephalus truncatus Pallas, 1781 (Cestoda: Spathebothriidea) in its Intermediate and Definitive Hosts in a Trout Stream, North Wales

Abstract

Of the three species of fish which live in Afon Terrig (Salmo trutta, Cottus gobio and Nemacheilus barbatula), only S. trutta was infected by Cyathocephalus truncatus. The parasite has a clear annual cycle and hence a periodicity of occurrence in the brown trout.No age resistance of fish to infection by C. truncatus is found. The increase of incidence with age among l+—3+ year-old fish and decrease in the older age groups are correlated with the variation in the food and feeding habits of trout with age.