This note reanalyzed specimens and data of Boleophthalmus sp. (Ryu, 1979), Scartelaos gigas (Iwata and Jeon, 1987), Scartelaos gigas (Chu etwu, 1985) for critical note on the classification of Boleophthalmus and its one allies. It is found that Boleophthalmus sp. must be substituted to Scartelaos sp. The following characteristics are useful for taxonomy of them; Pectoral finrays, body depth in percentage of standard length, body depth in percentage of head length, snout length in percentage of head length (Wu, 1985), caudal peduncle depth in percentage of caudal length (Wu, 1985), type of upper jaw teeth and below jaw teeth, colar type of 1st dorsal fin, colar type of head part. These characteristics may be splited into three forms as shown in the next key; 1a. Mandibular teeth obiquely notched Scales small, about 100 L.I. ........................................................................... Boleophthalmus 1b. Mandibular teeth pointed, scales minute, rudimentary, about 200 in L.I ..... .................................................................. Scartelaos ... 2 2a. Dorsal fins V, -I, 25-27. head part of with yellow colar of band. Lower side of head with barbels .............................. S. gigas Chu et Wu 2b. Doreal fins V, -I, 24-25. head part of with white colar of three band. No barbels on head...............................................................S. sp