4 Dead Fishes In A Day

[kashifmasud]

Hi,
 
I have got 180L Cycled tank for couple of years now. Due to change of Job, I had to move to different city last week, so decided to put my fishes in small hospital tank & empty the main tank and move to the new place. I know what you guys will be thinking but it wasn't possible for me to keep as much water in the main tank...so I did my best, not to clean the filter...
 
So while the tank was empty I thought I should polish the tank from inside, ordered cerium oxide solution online, spent an hour to get rid of the minor scratches & water scale from the tank. Cleaned it well. I also decided to change the sand & put the black gravel instead. Got it from Petsathome, washed it, left it to soak & then put that in the tank.Now filled the tank, setup filter everything to run the tank...Because the fishes were in the hospital tank for days, I thought it would be better if I put them in main tank along with the hospital tank water.....Now obviously few of them were stressed but others were doing fine...Next day came back home, found 3 smallest fishes dead. I panicked so did a small water change, went out with friends for movie came back the biggest, oldest & favorite angel was dead...shocking as she didn't look stressed and actually was doing fine......In panic i took all fishes out, put them in hospital tank with fresh water in it...As the first thing came in mind, that tank water might be toxic....but how ?
Checked water conditions for hospital tank, Ammonia, Nitrite & Nitrate all good...Checked Main tank same, all good. So I am unable to understand what went wrong...btw 24 hours past my fishes seem more relaxed in hospital tank then they were in Main Tank...
 
Now I plan to change if not all, at least 80% water in main tank unless someone has any clue what could be wrong...Polishing solution says non-toxic (even if a drop or 2 got left in the tank) or is it the gravel but i thought they are suppose to be non-toxic...
 
Any suggestion would be appreciated...New Job, New place & the house was tiring enough that this happened...I got so frustrated that i was thinking to stop keeping fishes may be...
 
Thanks for listening...
 

 

[Ch4rlie]

Hmm, changing all the gravel would have affected your bacteria needed, not all bateria is found in the filter, they are all over the tank, substrate, glass, plants, decor etc, so that may have affected the fish with nitrite and/or ammonia poisoning during the short time they were in that tank.
 
Did the fish show any symptoms at all before they passed away?
 
The polishing solution may be a factor also, but without knowing what is actually contained in that, I am no scientist so am unsure what cerium oxide solution is, so thats hard for me to determine. Its certainly possible some toxic solution was left, perhaps some active carbon will help remove, if any, toxic solution or metals.

 

[Byron]

I also don't know anything about cerium oxide, but unless it specifically says it is safe to use on aquaria (inside), I wouldn't.  According to the safety sheet here
http/www.solvay.com/en/binaries/Cerium_dioxide_GPS_rev0_Sept12_RHD-139543.pdf
it has low water solubility, but that means it still is soluble in water.  Within the closed confines of an aquarium, something like this might be deadly.  And I've no idea how one would remove it, if it is even possible.
 
I would have suspected a cycling issue, but if your "all good" for ammonia and nitrite means they tested zero, this seems unlikely.  And before ammonia or nitrite killed the fish, you would probably have seen other symptoms: rapid respiration, lethargy, hanging near or at the surface, gulping air, red gills, flared gills.  Of course, such symptoms as these would have been applicable to the cerium oxide as well.
 
Did you check the pH and GH?  Shock from either if they were significantly different can be very serious to fish.  There really is no such thing as acclimation within a few hours if the GH in particular (and TDS) are far apart.
 
Byron.

 

[kashifmasud]

I have not checked pH yet but i thought if fishes are doing fine in hospital tank (with same tap water) then its pH should be fine too in main tank (not to mention i keep bogwood too to lower pH). Fishes didn't show any particular symptoms particularly those died, even dead i couldnt see any spot or red gills...looked fine to me tbh. And because it was quick I couldnt figure out their behaviour. Cerium oxide solution is available on amazon for glass polish/scratch remover, but tank was empty when I used it and cleaned it well. So I didnt think it could be the issue, may be ammonia level might caused a peak at some time ? But when I checked levels yes Ammonia, Nitrite, & nitrate all were zeros.
 
But I am planning to do large water change and monitor the conditions for couple of days before rehoming fishes in the main tank. Will keep it posted

 

[Byron]

Cerium oxide solution is available on amazon for glass polish/scratch remover, but tank was empty when I used it and cleaned it well.
 

 
This cannot be a certainty.  Any chemical used on the inside of an aquarium is risky unless it is specifically intended for this purpose.  This applies to silicones, for instance.  Some aquarists have used ordinary bathroom silicone to repair a tank, and it will poison fish.  The substances in these products will leech into the water when submerged.  Now, I'm not saying it was the cerium oxide, but I am stressing that no substance like this should be used on the inside of an aquarium unless the instructions specifically state it is safe for fish tanks.
 
If the fish are recovering in the smaller tank, we can be certain that something in the main tank is responsible.  Issues such as internal fish protozoan that are undetectable externally can be ruled out if the problem goes away in a different tank as you indicate here.
 
The pH can be vastly different between tanks and tank and water source.  A pH test kit is something you should have on hand, as when fish begin showing signs of trouble, checking pH along with ammonia, nitrite and nitrate (and temperature) is a basic first step.  I always follow the tests with a major water change as this can determine if the issue is in the water or in the fish.  In your situation, changing tanks was like a water change, and the improvement tends to suggest water rather than fish.
 
Byron.

 

[kashifmasud]

I suppose you were right, I have checked pH and it was high 8.2 as compared to 7.2 previously I had. I went to LFS and the guy said 8.2 is normal here in this city, so I have got some med that lowers pH for now before fishes can acclimatize...But I hope my fishes do get acclimatize...btw with pH now lower fishes are doing much better in main tank...
 
Now I have 4 bolivian, 1 angel, 2 sword tail & 1 cory...do you reckon they will be fine at 8.2pH ? 

 

[Byron]

I suppose you were right, I have checked pH and it was high 8.2 as compared to 7.2 previously I had. I went to LFS and the guy said 8.2 is normal here in this city, so I have got some med that lowers pH for now before fishes can acclimatize...But I hope my fishes do get acclimatize...btw with pH now lower fishes are doing much better in main tank...
 
Now I have 4 bolivian, 1 angel, 2 sword tail & 1 cory...do you reckon they will be fine at 8.2pH ? 

 
First, do not mess around with the pH.  This is more complicated.  The pH is closely connected to the GH (general hardness) and especially the KH (carbonate hardness or Alkalinity).  The KH in particular acts as a "buffer" to prevent pH fluctuations, and the higher the KH the stronger the buffering.  Using chemical solutions to lower pH will not work long-term and the resulting pH fluctuations down and up will be very bad for fish.  Monitor the pH closely, as it may have lowered but I would expect it to be back up where it was within 24 or so hours, unless your GH/KH is very low.  But please do not use more stuff to lower it if it has, leave it where it is.
 
Track down the GH and KH of your municipal water and give us the numbers.  With these we can consider what if anything should be done.  And GH is actually more significant for fish than the pH, as the GH is the amount of dissolved mineral in the water and some fish have specific preferences.  Swordtails for example will be better in moderately hard or harder water, whereas Bolivian Rams and angelfish are better in somewhat softer water.  But this too is general, and without knowing the exact numbers we are guessing.  You can ascertain the GH and KH from your water authority, probably on their website.
 
Now, having said that, I would be very surprised if the initial issue was related to the GH or pH, as the store's water is likely to be much the same.  And so would be the water in the smaller tank, which offered relief to the fish previously.  I don't think there is any doubt that something toxic was in the water, whether from the cerium oxide residue or ammonia/nitrite, or...whatever.
 
Byron.