Fish dying!

[hoppershaun]

Hi Guys,
I'm having a problem with fish dying, and i can't understand why. Last week my gold gourami suddenly died after looking fine. One day he was swimming around normally and the next he just fell to the bottom of the tank. Also today an angel died, again there didn't seem to be anything wrong with it until I got up today to find it dead. I'm worried somethings wrong in my tank. I've had a few other deaths, a couple of rummy-noses and a harlequin rasbora but I put that down to bad acclimitising. Ammonia and Nitrite are both 0 and have never changed since the tank was cycled and Nitrate never gets above 10. I'm a bit worried that they aren't getting enough oxygen but there is plenty of water agitation, the nozzle from the power head is practically vertical so there is plenty of movement.
Any advice would be appreciated.
Thanks

 

[Zagz]

Any physical symptoms at all? Anything new added to the tank? Perhaps a contaminant got into the tank?

 

[hoppershaun]

No physical symptoms I've just been stocking the tank so all of the fish are relatively new additions. I had an outbreak of white spot on my harlequin rasboras but that seems to have gone away now after raising the temperature. Everything else in the tank looks fine, all healthy from what I can see.

 

[Zagz]

What kind of test kits are you using for ammonia and nitrite? Test strips can be inaccurate. It is possible that you might have had an ammonia spike due to the new fish additions. Did you purchase the fish that died from the same lfs? It may be the lfs had some fish that were already sick before you got them.

 

[hoppershaun]

I use the liquid drops test kits. Definately no spike in the ammonia, i check it very regular. Bought the fish from the same lfs, so yeah that maybe the problem.