I had a mated pair of Mandrin gobies that dissappeared for some reason. I put in a scooter blenny, and thought they may not get along, but never saw any "fights" or anything. I NEVER feed phyto to my tank, and wonder if the 3 fish could have depleted the pod population enough to starve out the 2 mandrins? I have a 180 with about 240 to 280 lbs of live rock.