I have the same tank, and like all things reefing... it depends. What kind of fish would you like, where in the water column will they be? Do you have enough rock or another way to remove ammonia and nitrite ? Is there enough space for them to hide? Other various questions
I currently have 5 fish in my fluval, 2 clowns, a midas blenny, a pearl china wrasse, and a mandarin goby. Which is honestly pushing it... But they also occupy different areas of the tank and only crowd each other when I add food. My clowns stay below the overflow, the blenny stays under the return pump in a cave, the wrasse is everywhere, and the goby takes the left half of the tank to himself.