Underwater images and manual tags of different fish taxa detected from the image repository of the OBSEA Cabled Observatory from January 2013 to December 2014. OBSEA station is located 4km off-the-coast of Vilanova i la Geltrú (Catalonia, Spain) at a depth of 20 meters . Tags are rectangles marking the fish position in a picture (region of interest), identified by their x/y vertix values (in pixels).The aim of this dataset is to train Artificial Intelligence (AI) algorithms to automatically detect and or classify fish specimens from underwater pictures.Two cameras were used (Sony SNC-RZ25N from 2013-01-01 to 2014-12-11 and Axis P1346-E from 2014-12-11 to 2014-12-31). 29 fish taxa have been visually identified and classified according to their taxa name. Unclassified fish have been marked as Unknown fish.The fish taxa recognized in the dataset are: Coris julis, Chromis chromis, Diplodus vulgaris, Diplodus sargus, Oblada melanura, Spondyliosoma cantharus, Diplodus cervinus, Diplodus annularis, Spicara maena, Dentex dentex, Diplodus puntazzo, Conger conger, Symphodus mediterraneus, Atherina sp., Scorpaena sp., Pagrus pagrus, Pagellus sp., Serranus cabrilla, Sciaena umbra, Sarpa salpa, Trachurus sp., Sparus aurata, Apogon sp., Seriola dumerili, Thalassoma pavo, Epinephelus marginatus, Boops boops, Symphodus cinereus, Symphodus tinca.