Abstract
Three hundred and thirty-one turbot and 350 brill of varying ages were examined for infection with the tapeworm Bothriocephalus scorpii (Müller, 1776).This survey showed that: (i) turbot and brill acquired infections of B. scorpii before they were 1 year old; (ii) all the adult turbot were infected with B. scorpii, often heavily, whereas only half the adult brill were infected and then only slightly; (iii) differences in the structure of the gut mucosa could account for the strong attachment of the scoleces in turbot compared with the loose attachment in brill.