This is an eleotrid (sleeper), not a goby. It looks like Ophiocara porocephala, the Northern mud gudgeon. The species grows up to 34 cm. It lives typically in brackish habitats, including estuaries and river mouths.

The (overwhelming) prevailing usage is Ophiocara porocephala, so in spite of Kottelat's (2013) formal decision the name should not be changed. The Catalog of Fishes online needs correction in this respect; we will do this in the next posting.

thanks a lot to both of you!