The skimmer in pix probably won't be able to keep up with heavy bioload. I think it's best that you invest in a nice skimmer before trying to populate new fishes.
Introducing a few small fishes such as clownfish, gobies should be good until a better skimmer put in and species such as Tang or dwarf angels can be introduced.
Another small detail when you're ready to introduce these new fishes in, try to feed them as little as you can and watch them consume all the food within 5 minutes. If they are unable to finish all, lessen the amount of feeding a bit next day.
Looking at your signature, looks like a 90G tank is in the planning. Are you planning to keep the 54g along with the new 90G or just one tank when done? If only one, it is probably wise to get a skimmer that can also support the 90G tank and save money in the future for more fishes + corals.
HTH,
KLee