I read in reef keepers anual you need 75 pounds of live rock to succesfully keep a mandrin.Also should have your tank running for at least 7 months.I have about 70 pounds of rock,but my mandrin eats every thing I put in the tank.Most wont eat like this so I would get at least a 50 gallon with lots of rock.Or atleast fill up your 20g and just wait a few more months.
|