The fish is quite shorter than the members of Ptereleotris, and it seems to belong to other genus (of true goby), but I am not sure. Any other reply or hint ?
I found a little better pic of the one I was thinking of. It even has the lanceolate tail. The body does appear a little too short though. Maybe it is a virtue of the camera angle? Can you get any other pictures of the fish Dr. Tanaka, or was this taken in the wild?
I did not notice its name until now. The eye is bright blue. The last photo may show an adult coloration with green and blue. Mine is only 4cm long and is almost colorless.