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Danio died, one more seems to be gasping.

4K views 8 replies 6 participants last post by  microsoft 
#1 ·
Hi, I recently moved my 5 danios to my 90gal to help cycle it. They were happy and normal. Today I did a large water change and noticed afterward that they were not swimming all over like they normally do. We went out to get a movie and when we came back one was dead :(. He looked healthy, no sign of disease. Now I am worried because there is one other one who is swimming around the top of the tank, slowly. The other three seem to be ok. Levels are currently:

PH: 7
KH: 4
A: 0
NO2: 0

Before I did the water change the PH was around 6.4. Could this PH spike have caused the fish to die? If so, what do I do now and how do I prevent this in the future? I think this other one will die soon, he does not look good.

Thanks.
 
#2 ·
the quick change could have and the other thing that comes to mind is not enough oxygen. fish swimming at the surface gasping is usually a good sign of low oxygen levels. do you have a good air pump and air stone/pipe?
 
#3 ·
No air pump but the output of my canister filter is above the water level so it agitates the water.
 
#4 ·
So far so good. So how am I supposed to do water changes to avoid this in the future?
 
#6 ·
The remaining 4 are OK this morning. Weird thing is that the one who died was really pale and small before I moved them to the 90gal. Once I did his stripes came out and he looked great....then he died. So my guess is that he was weak to begin with....
 
#8 ·
Sorry to hear about the loss of the fish. How large of a water change did you do? Do you add dechlorinator to the water?

I know the water from tap contains CO2. As it sits, the CO2 is degassed, which will cause a change in pH. That small of a pH shift should not be a problem for the fish.
 
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