Alfredshouse is gone.....

[fkshiu]

Originally Posted by Jack

You keep saying Nitrate - which is not really toxic to fish.

If you say Nitrate (No3) being 0.8 - I think you mean Nitrite (No2) - which is very toxic.

Sorry about your loss.

It was just too many fish added at once.

Bummer.

Actually, nitrITE in marine aquaria is relatively NON-toxic to fish:
http://www.reefkeeping.com/issues/20...hf/index.php#5

What is concerning is the presence of nitrITE in the water at all which almost always means that ammonia (which is very toxic) was there previously. There should be zero nitrITE in a tank more than a year old unless there was a mini-cycle - possibly brought upon by the addition of so many fish at once.

I believe that the oxygen deprivation theory may be correct especially if the FX5 was the only form of circulation: Lots of fish are added to a tank with poor circulation. This causes the death of the weakest fish which in turn causes a mini-cycle which kills off the rest. When you finally do the testing the cycle is at the stage where's there's a little nitrITE left and rising nitrATES.

Your Alk reading is actually normal.

[Myka]

^ I think fkshiu is on the right track. I don't think it was a single issue that caused the death of all the fish, but in the end I do believe the primary cause was adding too many fish at once...then the resulting lack of oxygen and (likely) ammonia, and who knows what else may have also played a factor.

[Jack]

Originally Posted by fkshiu

Actually, nitrITE in marine aquaria is relatively NON-toxic to fish:

Nitrite is toxic.

[fishoholic]

So sorry to hear about your losses

I have had a lot higher nitrates then 20 before in my tank, did some water changes right away once I realized, and luckily I didn't loose anything. The nitrates probably spiked after the fish died, doesn't seem likely to be the cause of death IMO.