Coral reefs inside Cartagena Bay have disappeared, largely due to the constant discharge of contaminated, sediment-rich freshwater from the Dique Channel. Recently, which might be the last healthy coral reef in the bay was found between Bocachica and Barú. Despite the unfavorable conditions for coral development, this reef exhibits an average coral cover of around 45 %. To study its fish diversity, inventories were made between 2015 and 2019, based on censuses during errant dives, band transects, photographs, and video recordings. A list of all fish species observed at Varadero reef, where 147 species belonging to 49 families have been recorded is presented; seven of those species (5%) are cataloged under threat. This study is the first approach to the fish diversity in this unusual reef, and a starting point for future studies that address the functionality and proper conservation of this ecosystem, currently threatened by projects that seek to dredge it.