Mugil longicauda differs from Mugil curvidens by the following: body depth (19.8-25.5% vs. 22.8-33.3% in Le); smaller head (17.8-20.2% vs. 26.2-34.2%) in SL or 5.0-5.6 vs. 2.9-3.8 times) in SL; insertion of first dorsal fin in closer to the snout tip than to the base of caudal fin in vs. equivalent; insertion of the second dorsal fin is about the middle of the anal fin vs. only slightly after the insertion of the anal fin; teeth long and their tips are upward vs. tip curved toward the interior of mouth; axillary scales only present in the pelvic fins vs. present in both paired fins; caudal peduncle is longer (6 vs. 5.3-5.6 times in SL); A III,9 vs. III,8; presence of a yellow-orange blotch on the opercula vs. absent (Ref. 101267).