I have a 75 gal tank running for about 4 months it is a fish only with live rock. I currently have 2 clowns, 3 damsels and a mini anemone. I just recently lost a coral beauty, pearl scale and a Fox face all within the last 2 months all were added at separate times. All of the fish were doing fine and then from one day to the next day died. When I test my water my ammonia levels are extremely high and no matter what I have done from water changes to adding a ammonia detoxing agent nothing is making it go down. What’s strange is that the remaining fish are doing just fine. Any suggestions on what could be causing the spike in ammonia?