The tank should clear up on its own. Did you rinse the gravel and decorations thoroughly before adding them to the tank?
I would not add cycle to your tank. It does not actually help to cycle tanks. Make sure that since you have a fully stocked tank already that you are doing daily water changes so that the fish are not harmed by the rising
ammonia and
nitrite levels.
You do not need to add salt to your aquarium. Your fish are all fine in regular freshwater.
By the way, you will probably encounter problems in the future due to the stocking of your tank.
goldfish should not be housed with other
freshwater fish because they thrive in lower temps than most tropical fish do. Your two plecos will definetly outgrow your tank. A 55 gallon is large enough to house 1 common pleco by itself. I do not mean to criticize you, I am just trying to help you prevent future trouble with your tank. I know how frustrating it can be when things go wrong, and I would hate for anything to happen to your fish.