This article provides a checklist of the aquatic animals the Romans appear to have recognized, including an overview of how they classified and named them. Indeed, in addition to providing scientific identifications of the animal referents and philological and/or linguistic data related to their names as they emerge in the ancient texts, the checklist focuses on ethnobiology. In particular, it provides ethnotaxonomic and ethnobiolinguistic data such as ethnotaxonomic rank and ethnobiological name typology (Conklin 1968; Berlin 1992) by which to reconstruct the actual folk taxa, i.e. the kinds or “groups of kinds” of animals each name covered in the ancient speakers' minds (but a few unnamed folk taxa have also emerged). In this respect, tree diagrams are used to represent at a glance the folk taxonomic knowledge of an ideal Roman as to the main higher-order groupings of aquatic animals they were familiar with. The results are analyzed and statistical data are provided as to various relevant ethnobiological variables. The findings accord with Berlin's universals, except for the number of additional levels where folk taxa of the life-form rank can be found, a characteristic already observed for aquatic animals in other folk taxonomies (Pawley 2006). From a more general zooanthropological perspective, these data suggest the Romans' familiarity with the aquatic world and its inhabitants, despite their traditional self-ascribed identity as peasants and soldiers.