White spots

[redstar_369]

Hi guys...My tank don't have any problem till I introduced a powder blue tang about 3 weeks ago.I hardly see it eat during feeding time.The rest of my live stocks are fighting for food.Not long after,white spots appeared on my powder blue tang.It gets worse at times and back to normal sometimes..

It finally died a few days ago I've done a 20% water change before that but it didn't help.Everything was back to normal after that till I realised that even my maroon clown was infected this morning when I woke up.I'm surprise that a hardy clown was infected too..The rest of my corals and live stocks are still ok.Just that my green chomels are missing day after day...What is exactly wrong with my tank???

My tank is 4ft X 1.5ft X 2ft.

Im using a chiller at 26 degree c

My tank is a reef tank with lots of live rocks and corals.

I left with 7 green chomels,1 fox face,1 algae eating benny,1 sick clown

Invertabrates are 3 cleaner shrimps,1 boxer shrimp,2 turbo snails and 1 star fish

Can anyone out there give me some advice coz I can't use copper.

[Dispar_Anthias]

Go read on this topic in the disease treatment forum, i believe its been ask many times

[steven]

Check your water condition namely ammonia, nitrite, nitrate. make sure the first two are undetectable and nitrate < 20.

Basically prevention is better than cure in a marine tank. So ensure the best condition for the fishes first.