Larvae of tetraphyllidean cestodes have been recorded in several species of marine teleosts. However, little is known on parasite-host interactions. In view of this, the present study aims at i) determining the localization sites of a larval type, belonging to the Scolex group, in the digestive tract mucose; ii) describing the anatomo-pathological features of the larval lesions produced; and iii) evaluating the potential effect of parasite intensity on the body condition of the host. Our findings reveal that parasitic charges were more intense in the second portion of the digestive tract. In the area of contact between the parasite and the epithelium a compressive atrophy of the cells was observed with a marked lowering and disappearance of the epithelial layer. The condition factor of the samples analyzed was significantly affected by infection intensity, thus revealing an adverse effect on the growth and physical condition of the host.