Liopropoma santi, like two other related bass species, L. aberrans and L. olneyi, has a golden body but can be differentiated from other Liopropoma species in the Western Atlantic in a number of ways. The diagnostic feature of the fish is the presence of a dark spot on the lower part of its caudal fin (tail fin), which feature gives the species its common name.[5] The lower part of the fish body is of a colour ranging from pale yellow to white.[5] The upper lip of the fish has a yellowish to orange coloured stripe along it and it has a series of white, striped markings on the ventral portion of the trunk resembling "chevrons".[2] The dorsal fin has 13 spines and an indented margin.[2]
The specific epithet santi commemorates Roger Sant, a philanthropist and supporter of the Smithsonian Institution[6] who was present at the crewed submersible dive in which an exemplar of L. santi was collected.[4]
Of all the species of Liopropoma, L. santi resides at the deepest levels of the reef, having been sighted only between 182 and 241 metres (597 and 791 ft).[5] When approached by a submersible with lights it took shelter in caves and crevices in the reef.[7]
