Have you been testing your water parameters? I'm off the opinion that you are probably having a water chemistry issue (the tank is not completely cycled) as well as some stressed out fish.
Even though the fish you had may have been small, you had two angels which both get pretty large as well as a surgeonfish that gets decent sized and requires a lot of room to swim and be happy. On top of that, a puffer and a clownfish, all in a 30 gallon tank. (Even the 55 won't be big enough for all these guys long term.)
If you don't have liquid test kits, I highly recommend that you invest in some. The API Saltwater Master Test Kit goes for about $32 in an LFS, and about half of that if you mail order.
Your tank starts out as a pretty much sterile environment, and when animals are introduced, they begin to produce waste and there is nothing there that can convert their waste into less toxic compounds. We measure this first as ammonia. A type of bacteria wil eventually begin to grow in the tank which will then convert that into compounds we measure as nitrites, which are still toxic to the animals in the aquarium. Yet another type of bacteria moves in and converts nitrites into nitrates, which are far less toxic than the ammonia or nitrites. If you havde measurable ammonia or nitrites in your tank, the tank is NOT cycled. You will still need to work to keep your nitrates low via water changes or some other nutrient export method.
There are some great articles on this site which can walk you through how to get your tank to cycle without risking any fish. It's boring, but a lot less traumatic and less expensive. The easiest method IMO is in the link below:
Cycle your salt tank - Aquarium Advice
By the way, all three kits (ammonia, nitrite, and nitrate) as well as pH are in the API Saltwater Master Test Kit.
