It is a yellow clown goby - both you are right.  Goby's do have a noxious slime on their bodies that make them less edible to larger fish - leaves a bad taste in their mouth so to speak =).  I am uncertain as to whether or not this slime directly affects the corals but I have heard many stories of the negative effects that goby's can have on corals.  I love their personality though - which is why I keep mine! 
		
	
		
		
		
		
		
	
		
		
	
	
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