Interesting. This is from a Coral Magazine article November 2010...
http://coralmagazine-us.com/content/myth-shrouded-spikefin-goby
However, the least complicated method of feeding the Spikefin Goby is to not actively feed it at all!
This suggestion may appear risky at first glance, if not completely irresponsible, but it isn't: because D. griessingeri lives on benthic zooplankton such as is available in abundance in any healthy aquarium biotope, and because the nutritional requirements of these tiny fishes are comparatively small, then given suitable conditions this little goby can be nourished extremely well using what its environment provides.
I guess this is one of the things I remembered reading, although not accurately. It does not sound like a real scavenger, but it also does not sound like it needs to be directly fed.