take the salinity up to 1.025 by adding more salt when you do a water change. only take it up by .02 per water change. might also want to take the temperature down to 75 f.
when you acclimate the fish you should use the drip method instead of just floating them in the bag. it seems like your fish went into shock upon entering your tank. for the drip method you need a 5g bucket, and plastic tubing. empty the new fish into the bucket along with the water thats in the bag, find something to tilt to bucket with so the fish is fully submerged, place one end of the tube into tank, take the other end and tie a knot and suck to create a siphon, place the knotted end into bucket, tighten knot so there is a fast steady drip. you should be able to see the individual drips, if it is a stream then it is too fast.
that is not your only problem. you should also have 1lb of live rock for every 1g of water. this is the minimum. the sand bed should be about 2 inches. more is always better.
