For the gobies and the mandarin fish I'd put a ton of rubble behind your rock, the more rubble the more hidding places for pods. Make it inpeneratable to fish and you could have a good pod population in a year. The refugium is an excellent idea, a few pairs of shrimp in there will provide lots of larval food as well for your fish. 
 
Doug 
		
	
		
		
		
		
		
	
		
		
	
	
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