Thanks, I was told it was an African rock goby- Sicydium crenilabrum
I have over twenty gobies, mostly Stiphodons ( 'Gold spot' and 'Rainbow') and ( what it seems-) Syciopus jongklasii , which are getting red lipped or red all over when they are getting in the mood ( +feeding time with live black worms). My Stiphodons are omnivorous. What I miss is Stiphodon percnopterygionus, but whatever is advertised under this name, is not it!!!
Another problem with Gobies is that the trade is mainly in males, so one misses the mating displays, and this is the time when they look their best.
I love Gobies!!!
What I noticed after trating my tank with Panacur for Hydra, is that my Gobies become much more vigorous in their swimming and often I see them in the middle of my tank ( 180)