a Court Jester goby,

I`m a little late on this thread---sorry. The court jester goby is a
Rainford`s Goby, right? Does he constantly bite the substrate and sift
through his gills?

I`m pretty sure those guys are voracious pod eaters. I have a Hector`s Goby,
which is very closely related and shares the same behavior. When I
researched buying him I read somewhere that when disected, their stomach
contents revealed something like 70% copepods.