Fish Dying- white cotton stuff

Question
I would consider us newbies at our 58 gallon aquarium.  Have had and still have a successful 10 gallon but can't seem to get this big one together.  Our water tests perfectly (took it to two local pet stores for analysis). We had 9 tiger barbs and then we added a silver tip catfish shark.  All was well until we added a red tail shark and two kribensis.  The silver tip then got ick.  We treated with Rid ick + for 5 days.  Last night, after we put the Rid ick in the tank, we started to notice the fish beginning to look "not well".  This morning, the silvertip is gone and 3 barbs have died since. We probably have been overfeeding them but that was weird too.  They were eating much more and then stopped all of a sudden.  We didn't adjust the food enough and the leftovers got fuzzy. Tonight, more fish are looking worse.  What do we have and what should we do?  Should I put the remaining 6 barbs in the 10 gallon guppy/platy tank?  Please help."

Answer
I no its not that easy to get started is it?
I suggest you keep the fish in the tank and carry on as normal because things may settle down.I think what you should do is feed them less and put small amounts in at a time so the fish eat all the food you put in with the minimum food particles hitting the floor.
I think that you have new tank syndrome so try adding cycle to the tank.