About Stigmatogobius sadanundio (Hamilton, 1822)
This gray-blue fish has two dorsal fins. The first dorsal fin has approximately six stiffly held rays, and it often bears a black blotch. The second dorsal fin is equal in length to the long-based anal fin. Both of the dorsal fins carry dark spots. This species can reach a maximum length of 9 centimetres (3.5 inches) in standard length (SL).