fishface, 
 
Not that I have actually done this, but I have read that putting the mushroom in a small container of rubble in a low flow area of the tank will allow the mushroom to attach to the rubble.  Once it has attached, in a few days or a week or so, you can place it anywhere in your tank that is suitable. 
		
	
		
		
		
		
			
		
		
		
		
	
		
			
			
			
			
			
			
			
			
			
				
			
			
		 
		
	
	
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