• The fish acanthocephalans P. laevis and P. tereticollis show moderate specificity and low niche overlap. • Transmission bias from shared intermediate hosts towards either benthic or bentho-pelagic fish is evidenced. • Decreased taxonomic specificity towards fish hosts matches with lower prevalence in intermediate hosts. • Lower worm size in the host with the lowest abundance calls for further investigation of compatibility filter. • Low taxonomic resolution within some parasite species complex hinders accurate estimate of host use pattern.