Background. In the Mediterranean Sea, habitat preferences of small benthic fishes of shallow waters have been poorly investigated. Although combtooth blennies are not of interest for fisheries, they are often the dominant fish community on rocky bottoms within the first meter of depth and in tidal pool environments, playing so an important role in the functioning of the coastal ecosystem. This study represents the first detailed investigation concerning habitat preference and depth distribution of combtooth blennies in the Ionian Sea. Materials and methods. Occurrence and abundance of species were investigated by a non-destructive visual census method using snorkelling or SCUBA diving. We investigated 5 habitat types (bathymetric intervals between 0 and 3 m of depth) to find difference in species richness and abundance in each one and between. Studies were conducted from June to October 2014 in the south-eastern coast of Sicily. Statistical method of the electivity index (EI) and principal component analysis (PCA) were utilized for the evaluation of the habitat preference of 11 species of combtooth blennies.  Depth distribution for each species was box-plotted. For each habitat and depth, the Shannon–Wiener Index (H’) and the Simpson Index (D) were calculated. Diversity profiles were performed in order to give a better understanding of the correlation between diversity and both habitat types and depth. Results. During a total of 2485 observations of combtooth blennies a total of 11 species were recorded: Aidablennius sphynx (Valenciennes, 1836); Coryphoblennius galerita (Linnaeus, 1758); Lipophrys trigloides (Valenciennes, 1836); Microlipophrys canevae (Vinciguerra, 1880); Parablennius gattorugine (Linnaeus, 1758); Parablennius incognitus (Bath, 1968); Parablennius pilicornis (Cuvier, 1829); Parablennius sanguinolentus (Pallas, 1814); Parablennius zvonimiri (Kolombatović, 1892); Salaria pavo (Risso, 1810); Scartella cristata (Linnaeus, 1758). The maximum Shannon–Wiener Index (H’= 2.335) and Simpson Index (D = 0.898) values were recorded on “rocks with algal cover”; while, concerning the depth, the maximum values of both indices were recorded within the first meter. The diversity indices showed the highest values in the most heterogeneous habitat types. There was a negative correlation between depth and diversity indices. Results showed  a clear habitat preference for the following species: A. sphynx, P. gattorugine, P. sanguinolentus, S. pavo and S. cristata. Conclusion. This study highlights the importance of depth and habitat heterogeneity in biological diversity, species richness and population abundances of combtooth blennies in the Mediterranean Sea.

microhabitat, cryptic species, habitat types, Mediterranean Sea, depth distribution, tidal pool, shallow waters