you shouldnt add any fish untill amonia and nitrites are zero and you need to wait for them to appear and then drop to zero then you should see a small spike in nitrates in which you can do a fairly large water change... you added way too many fish way too soon i only have 3 fish in my 33g that has been runing for years.i would advise to take out the dead fish and any living ones untill your sure youve completed your first cycle which will happen in time i guarantee. after of which you should add a cleanup crew
then 1 single fish .you should let your tank stabilize before adding anymore fish then. my rule of thumb is if your starting from scratch minimum month and a half before adding
any fish, and even then you really really really need to add them slowly.the smaller the tank the more these rules need to be followed.if you stick to this guideline your sure to have success without any losses.
once you have no nitrites or amonia and your nitrates are low you can think about adding hardy corals if thats your intention
some good advice is to read and be patient dont plan anything in your first month just watch your tank.... after your first month you can add a clean up crew for a couple weeks then thing about adding a small fish.
also never add liverock or anything that could hold dead organic matter to your tank or it will just start another cycle