Usually labelled as a flaming prawn goby around me - Never actually seen it labelled as a Greissenger oddly but then its considered quite rare to find these days too. Very pretty species.
No personal experience, having not kept one but i know a couple with one each and they always say how its a non-problematic fish to keep. feeds on pepared foods and is fairly active for its size. Just cannot be housed wiht any boisterous species for obvious reasons.
Your smaller tank will probably help with this species to settle though and i dont expect you to have an issue with the clown. Some can be aggressive but the common clowns ive kept over the years rarely show any interest in gobies, blennies etc.
Just be prepared with an arsenal of foods incase it is reluctant to feed in the beggining - Lobster eggs, fish eggs, copepods, etc. A good variety to be sure.
I personally find lobster eggs are great for the slightly iffy species of gobies as they are tiny in size - a small cube can cover a lot of ground and they sink so as they dont have to move much to find. Not being comfortable to move aorund in the begining is one of my biggest issues for any of the tiny goby specie sin my experience but lobster eggs tend to be great for this and enticing.
