Death of saltwater fish over 3 months

Question
I have a 48 gal.Fluval filtered tank, 40-50Lbs live rock with some mushrooms, 2 cleaner shrimp, starfish,2 clowns, dottyback,damsel,long nose hawk. Over time,royal gamma,flame angel, mimic tang,yellow tang,flame hawk and fairy wrasse have died after a few days to one week. Tank cleaned and water replaced monthly and water tested routinely. At a loss to explain loss of fish. Tank now about 4 months old and professionally maintained. Feeding frozen or pellets alternating days. Why are fish going so fast. Aquarium people puzzled too.

Answer
That tank was set-up WAY too fast.

You should give your tank about 2 months where there is nothing in it, just live rock and sand.

Then, in the third month you add some inverts like shrimp and maybe some corals. In the fourth month you add one fish, or a pair of fish. 6 weeks after you add another fish, and so on.

To have all those fish added in that short a time is insane. Also, the tangs should not be in there. They may not have lasted long even if they were added properly.

Also, you should be doing water changes twice a month, since you do not have a ton of live rock.

And you only have one damsel in there? Damsels are schooling fish, and there should be at least 4 or 5 in a school.

Somethings not adding up, if this tank is prefessionally maintain, they sure are taking a lot of shortcuts and cutting a lot of corners.

-Nick