Its a Glossogobius species. I think its glossogobius giuris, but it could be glossogobius olivaceus, from the top it looks like a glossogobius. But if it has a sucker mouth it could be an Awaous species, maybe Awaous Guamensis.
some species of rhinogobius , there are lots of species and subspecies of rhinogobius , many of them look similar superficially .Even difficult for experts to determine exactly which species without genetic analysis
