I have a 55, fowlr. I have about 70-80 lbs. of live rock. For critters, I have loads of snails, porcelain crabs, A couple of mantis shrimps(can't catch 'em), cleaner shrimp, coral banded shrimp, five pepermint shrimps, common urchin, large hermit, numerous small hermits, Foxface Rabbitfish, Powder Blue Tang, Coral Beauty, Ocellaris Clown, Convict Damsel, Yellow Damsel, Blue/Purple Damsel, Condylactus Anemone, Common Rock Anemones(from Fla. Gulf and Keys rock), Serpent and Brittle Stars. Pretty full bio-load, but I'm done until I get a bigger system.