Bro, just a piece of my experience for the past one year. I was like you, keep adding new fishes but end up RIP. Almost gave-up the hobby because fishes kept dying. Until I learnt from others that we need to stick to a lot of criteria in order for our fishes to be able to live longer. I believe in good skimmer, water parameter, water temperature, live rock and other factors. Ideally for a good kick-off, good water cycle is important. I got the bacteria from Henry(one month cycle). Now I dun see itch when I introduced my Powder Blue Tang. Main key for keeping marine fish is "Patient".