First general suggestion, do not start adding stuff to an aquarium with fish. Only water conditioner at a water change is needed, and perhaps plant fertilizer. Nothing else except as a specific treatment for health issues if one occurs.
Those "drops" are presumably some sort of water clarifier. They are bad for the fish; most clarifiers work by binding together the minute particulate matter into larger particles that can then be trapped in the filter media. Unfortunately, they also bind the gills of fish.
Salt is not needed in a freshwater aquarium. All soft water fish, of which angels are one, are sensitive to salt in minimal amounts. As for the puffer, if that is a
Dwarf Puffer they are freshwater. But I agree with a prior comment that puffers should not be combined with angels. But that is another issue, let's work on clearing the water.
Do you (or were you) doing regular weekly water changes of 40-50%, or was that just done for the cloudiness? And how long was the tank running before this started?
Byron.