Tank size in gallons for reference is 52.4 gallons
In saltwater u add ammonia and wait for it to spike up and completely disappear before adding anything. This normally takes a little over a month. Starter fish for this tank vary but I think gobies, clownfish, blenny, or cardinal fish may be a good choice. As far as stocking the tank goes stay away from any large fish like tangs, triggerfish, and large angels these fish can easily outgrow a tank that's 200 liters and they become quite aggresive when put in under their minimum tank size. Some fish that you could consider depending on if you want coral are
. Gobies
. Clownfish
. Blenny
. Smaller wrasse
. Dwarf angelfish such as flame angel IMO a flame would be cramped in that size tank and probably aggressive, I would look at a smaller dwarf angel such as a flameback or cherub /dwarf angels also aren't always reef safe.
. Cardinal fish
. Dart fish
. Filefish Not always reef safe/some get much to large for a 50 gallon tank
There are plenty of others u would look on the website live aquaria for reference.
Remember that clownfish do not need an anemone to survive.