The abundance and size of reef fihes in presence of lionfih were evaluated in Morro de Santa Marta, Remanso, and Isla Aguja and Chengue and Cinto Bays in the Parque Nacional Natural Tayrona (PNNT). Some commercially important fih species (Lutjanus mahogoni, Cephalopholis cruentata, and Haemulon plumierii) and some fih species important for reef health (Abudefduf saxatilis, Chaetodon ocellatus, C. striatius, C. sedentarius, and C. capistratus) were evaluated monthly during 2012. Counting was carried upon using visual censuses along 30 x 10 m transects. The highest lionfih abundances were found at Morro (2.60 ± 2.12) and the lowest at Remanso (0.58 ± 1.16), however, no differences were found between localities (p > 0.05). Highest abundance was recorded in June and July and the lowest in March, September, and October; no lionfih was observed in February. The highest abundances of both, commercially important and reef health important species were detected in the PNNT localities. The smallest lionfih and H. plumierii specimens were found at Morro, Remanso, and Isla Aguja. The size of the species was similar for all localities and lionfih sizes where larger. This may indicate that the studied species are not large enough to compete and thus they may be displaced, likewise their low abundances may be due to other stress factors. In any case, the invader has not reach yet the abundances shown in other Caribbean regions and then it may not be still causing a negative effect on the reef community.