Every Time I Add A New Fish It Dies !!

[evolution]

I have a 50 gallon tank it has been set up for 4 years I currently have a sixline wrasse and a marron clown fish that is still small. I have many different kinds of coral that it doing very well. I have had the fish for about 7months but every time I have tried to add a new fish it does fine for the first few days and then dies. I have tried adding a powder brown tang. 3 different naso tangs, a yellow tang, and 2 different dottys with no luck. I have been trying to add new fish over the course of the last 5 months but they all die. what could be the problem, Am I destined to have just the 2 fish that I already have? I have had my water tested and it showed that my salt ammonia and nitrites were all on target, my ph was at 7.8, phosphates were at 1.0ppm which the guy said was a little high, and my nitrates were at 50ppm he said this was a little high also. I have done a 20% water change and added the nitrate sponge granuals. He said that the levels that were a little high would have no bearing on the fish. Is he wrong ?

 

[promisetbg]

If none of those parameters mattered,then why would we check them?Think about it.
Of course they do...your ph is a bit off,it should be at 8.2-8.3.What is your alk. reading?SG.?
How are you acclimating these fish?
50 ppm is high on nitrate IMO.What about ammonia and nitrite?
When the fish die are there signs of trauma?Are they breathing heavy?
Can you give us a general idea of your set-up?How big is the tank,what is the temp,filtration method,skimmer..yes or no??

 

[dburr]

Well have you noticed that your maroon doesn't play nice with new-comers? They are aggressive in an established tank. Not sure what else it could be if you have done the things promised have said.

 

[evolution]

I know that the maroon clowns are typically aggressive but my is not at all. I would say that my six line wrasse is more aggressive. it even eats any shrimp that I add into the tank, and I have been told that the 6lines do not usually do this. I have not seen either fish pick on the new fish that I add. The newbies do not show any sign of truama or disease, no heavy breathing. they are eating and swimming around just fine and then BAM I wake up in the morning and they are on their side and dying at the bottom of the tank. I have a protein skimmer and a bio wheel filter about 125 lbs of live rock and 2 power heads. my ammonia and nitrite are at 0 my sp is at 1.025 my temp is 79 degrees

 

[wax32]

I've heard that Biowheels tend to generate nitrates. That could be contributing to your nitrate problem.