This species is distinguished and differs from Labidesthes vanhyningi by the following characters: Labidesthes sicculus have the anterolateral processes of the posttemporals longer than width of the base (vs. L. vanhyningi having the processes shorter than width of base); with a midlateral stripe tapering to insertion of pectoral fin in advance of first dorsal fin (vs. maintaining width or usually expanding, to insertion of pectoral fin in advance of the first dorsal-fin); a ratio of thoracic length to abdominal length greater than 2 (vs. less than 2) (Ref. 104856).