Inherited old tank crisis

[Familyfishny]

Hi folks,

My sister-in-law had a major die-off in her tank a few days ago. She decided to close down her tank, and gave me her surviving two fish. These are two fairly old bronze cories, a mated pair. She brought them over in a tiny tank for quarantine, in their own tank water. She had just done a 30% change (which triggered the die-off), and thought it would be best not to shock them any further. Good thing, because here’s what the nitrate test looks like. I just did a 10% water change before testing; I’m afraid to do anything more now, because I don’t want to shock them too much. Do you think 10% water changes for the next several days would be best, or do I need to do a bigger water change right away? I’ve never heard of nitrates this high. Their tank must’ve been like this for a long time. I don’t know if they’ve acclimated and clean water would kill them, or if they’re at death’s door and need clean water asap. Any advice would be most welcome.

Stats:
2.5 gal (I know it’s too small, it’s just until I can put them in my 37gal), substrate and cave rocks from their home tank.
Ammonia: 0
Nitrite: 0
Nitrate: somewhere betweeen 50 and 140? They all look crimson on the test strip key

 

[Slaphppy7]

I do a LARGE water change, with a good quality water conditioner...match the tap & tank temps as closely as possible

 

[connorlindeman]

I do a LARGE water change, with a good quality water conditioner...match the tap & tank temps as closely as possible

Wouldnt that shock these fish? Seems like they haven't experienced a water change in a while.

 

[Slaphppy7]

Wouldnt that shock these fish? Seems like they haven't experienced a water change in a while.

I'd take that risk...that amount of 'trAte needs to be brought down, sooner rather than later

 

[Byron]

Agree with above. There are two very important factors here. First is the parameters in general. Provided the GH, pH and temperature are reasonably similar, a substantial water change is preferable and more beneficial. Even the GH and pH can vary, one has to consider everything together. Temperature is far more critical. The pH should be watched though...if it is now in the tank water acidic (below 7), and if the tap water is basic (above 7), any change from acidic to basic could cause issues if ammonia is present. So check both in the tank water.

Second issue is the nitrate. This should be brought as close to zero as possible and immediately if the above is not a stumbling block. Fish do not ever "adapt" to forms of nitrogen, be it ammonia, nitrite or nitrate. The latter is poisonous to fish and like any poisonous substance the faster it is removed the better. Nitrate is much slower acting, and it is generally thought that its detriment is more of a weakening of the fish generally, which obviously causes further issues the longer it is left.

 

[Familyfishny]

Hi all, thanks so much. PH seems about 7.4; my tap water is 8.4. Ammonia is 0 or possibly under 0.25; the colors are pretty close. Is that too different? The big tank change is what killed all the other fish in her tank (2 goldfish, a panda cory, and something long and black and maybe 3.5”). These guys survived it, but…

I am home today and the tank is tiny; I can do 10% every couple hours if that would help… or I can do 50% a few times if fast is more important than careful.

 

[Byron]

Hi all, thanks so much. PH seems about 7.4; my tap water is 8.4. Ammonia is 0 or possibly under 0.25; the colors are pretty close. Is that too different? The big tank change is what killed all the other fish in her tank (2 goldfish, a panda cory, and something long and black and maybe 3.5”). These guys survived it, but…

I am home today and the tank is tiny; I can do 10% every couple hours if that would help… or I can do 50% a few times if fast is more important than careful.

Two things. First, the issue with the older tank and fish dying may be what I mentioned previously. We don't know the pH of that water, but if it was below 7 then any ammonia would be primarily ammonium which is harmless (for our purposes). A water change that raised the pH above 7 would turn any ammonium present into ammonia, and dead fish result. We don't have numbers for that tank water, but this is a frequent issue if tanks go without regular maintenance.

Second, to your tap water pH. If memory serves me, you have soft water in NY (if this is NY City area), and likely an acidic pH. But, the water authority may add something to increase the pH, this is common, I have to deal with this. Check with the water people, they must tell you if anything is being added, may be on their website. Also, let as glass of tap water sit 24 hours, then test pH and see what it is.

 

[StevenF]

I am home today and the tank is tiny; I can do 10% every couple hours if that would help… or I can do 50% a few times if fast is more important than careful.

I think smaller very frequent water changes are west in this case

 

[Familyfishny]

Hi Byron,

We live in upstate New York, which is on a different geology. Our water is from surface water that sits on top of limestone, so it’s very basic.

 

[Slaphppy7]

My local mom & pop LFS has a good variety of fish, I have purchased fish there often, and tested the water from the bagged fish, from time to time...no ammonia, no nitrItes, VERY high nitrAtes, similar to the OP's

When I informed the shop owner of this, she informed me that they use UGF filters in every tank (which I had failed to notice before), and that the filters are rarely (if ever) cleaned....IMO, the dirty filters are causing the high trAtes

When I get the fish home and place them into my QT tank (nitrAte around 7 PPM), the immediately perk up, their colors become vibrant, and they appear to be very hungry (I feed on the first night, and they are ravenous)...and most go on to live a very long time

PH at the shop is similar to mine; in effect, adding the fish to "clean" water does nothing but benefit them which is what a large WC would do in this case

@Familyfishny, when you say the tank is "small", what do you mean? What are the dimensions of the tank?

Follow the advice of @Byron above; draw a sample of your tap water into a clean glass or bowl, and let it sit undisturbed for at least 24 hours; test the ph of this sample, and post the results here

 

[Familyfishny]

Hi Slaphappy and Byron,

I have done a couple of small water changes, and a 20% change just now. The cories are still alive, but aren’t eating and their fins are pinkish. The tap water left out for 24 hours is pH 8.2. The small quarantine tank is 2.5 gallons; once their tank water more closely matches that in my tank,, they will go into an under stocked 37 gallon tank where I am still struggling with insufficient filtration but the water parameters are better (0, 0, 10). Given that information, how should I proceed with these cories?

 

[Byron]

From that photo I do not see any fin issue.

Tap water pH is 8.2 so that is settled. What is the GH in numbers? I would assume that the GH will remain much the same in the aquarium unless there is something in the tank that affects GH. What is the pH in the tank water for comparison?

 

[Familyfishny]

GH in tank is 180; GH in tap is also 180. Quarantine tank pH is 7.4.

 

[Byron]

I think the issue here was water changes, so on that note I see no issues in doing substantial water changes provided the temperature is basically the same. There does not seem to be much buffering of the pH, because it is lowering in the aquarium, so they may raise it with something like soda ash.

 

[Familyfishny]

Great! Thank you, both of you. I’ll get on that, and that will hasten their move to our bigger tank.