stocking ideas for a tank with sand/crushed coral?

[duanes]

Since the gobies are bottom huggers, you may want something that favors areas near the surface, or mid tank like some of the smaller Central American and Mexican live bearers which like hard water and would fit that tank. Zoogoniticus tequila is a favorite of mine.
If you are concerned with being geographically correct with the gobies (Australian), a couple dwarf feather fin rainbows would fit that bill
tequila below

 

[Gourami Swami]

I would go tanganyikan shell dwellers man. They are the coolest cichlid for a tiny tank IMO. Unique behavior with the shell homes, you can get a group of them (though only one male in this size) and watch them interact. Really fascinating little fish.