I've had my 20g long that's in my workshop going for a couple of years now. I have 2 Storm Clowns and a Rainford Goby for the CUC I have some Peppermint shrimp, Emerald crab, Conch, Nassarius and Trochus snails. I've found that if I go over 3 fish in this tank the one I add doesn't last too long. I've lost a Royal Gramma and 2 Firefish in the time this tank has been running. When I lost the last Firefish I added to this tank I realized that this tank does well with just the 3 fish and adding another disrupts the balance so I won't add anymore.