First check your water quality. Ammonia, Nitite & Nitate. Correct any problems. Fin clamping & sulking at the bottom can both be signs of problems.
2nd, the torn fins may be due to the fish flicking & scratching due to skin irritation, causes poor water quality or parasites. Watch your fish carefully - have a really good long look at each one. Look for ragged fins, spots or streaks of blood on fins or skin, clumps of cotton wool like stuff or a soft, raggedy patch on the skin. Anything which isn't a healthy, active, shiney fish.
An addition of aquarium salt (Very Important - NOT cooking salt.) can greatly improve & even cure ailing goldfish of all types.
1-3 grams per litre. Dissolve thoroughly, before adding gradually, stirring well to mix because the heavier salt solution will settle to the tank bottom & burn the gills & fins, to the fish. This dosage is often recommended for koi ponds as a prophylactic treatment over winter or on a permanent basis.
In the absence of a full examination, a salt bath is a good first choice treatment for fish that are off-colour. For a variety of reasons it is not always effective. If the fish doesn�t respond, further investigation may be required.