Nitrate levels are too high, even after a water change

[jijifish]

Hi,
I'm new to fish keeping and i'm looking after my parents fish for a few months..
Recently one of the goldfish died, it had a black spot on it? Could this be the black spot disease or from bad water quality?

I tested the water parameters and the results were
Ammonia: 0.25ppm
Nitrite: 1.0ppm
Nitrate: 160ppm.

Is it possible that the fish died because of the high levels of nitrate? Previously, I did a water change and 5 days later, the fish died. The rest of the fish are okay.

I did a 30% percent water change yesterday after seeing the results. I tested again this morning and the ammonia, nitrite have gone to 0. But the nitrate is still 160ppm. What should I do?
I cleaned the sponge pump filter on Sunday 25th June, when can I clean the canister filter? I believe that what is called, it says fluval underwater filter U3 on the box. I think it is clogged so that might be the reason why the nitrates are so high? The last time, the canister filter was cleaned on the 18th May. If I clean both within the same week, would I lose all beneficial bacteria?

Will daily water changes bring down the nitrate level? how much? 25% or 30%?

The fish tank is 31 gallons, it is an overcrowded fish tank with 7 fish but I can't do anything about that since these aren't my fish.

Sorry for so many questions, I'm completely clueless about everything and I can't reach my parents at the moment.

Any lead or any possible solutions will be very helpful! Thank you

 

[Wills]

Hi welcome to the forum

Has this tank been set up for long? If you've inherited it from your parents I'd guess so, so it should be a mature filter? When you cleaned it did you clean it with tap water or water from the tank?

If you had ammonia and nitrite readings in the water before the water change it might be good to understand whats going on there - when was the tank last cleaned?

160ppm for nitrates is very high and over time will shorten a fishes life but wouldnt cause a sudden death, black markings on some fish can be caused by nitrates though. Goldfish's colours change so much over time though so its hard to say if that is the issue.

Also just to check which test kit are you using? Is it the dip strips or a liquid kit?

Wills

 

[anewbie]

Have you tested your base water? In some areas of the world the drinking water has a high nitrate. It is unlikely that 160ppm nitrate would out right kill a fish as in the old days people didn't do water changes for years and while fishes do die it would sometime be after many years of ownership. That isn't to say high nitrate is not bad but the effect are more subtle over long period of time - as oppose to nitrite or ammonia which can kill fishes in minutes or hours depending on concentration.
--
Gold fishes are naturally 'dirty' fishes and i doubt your nitrate level had an immediate effect on the fish.

 

[Colin_T]

Check the tap water for ammonia, nitrite and nitrate.

If the tank hasn't been cleaned for a month or more before you took over, then do a 20% water change and gravel clean the substrate every day for a week. Then do a 30% water change and gravel clean every day for a week. Then 50% every day for a week. Then do a 75% water change each day until the nitrate is at 0ppm or whatever the tap water is.

If the tank was getting regular water changes before you took over, then do a 75% water change every day until the nitrates are at 0ppm, or at whatever the level is in the tap water. Then do a 75% water change and gravel clean once a week after that.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

--------------------

re: the black spot. Did you get any pictures of it?
Black spot is uncommon in fish and is normally caused by a parasitic worm.
Black patches can be bruising from chemical burns, which are normally caused by something bad in the water or washing the filter materials/ media under tap water.

I wouldn't worry about the black spot unless more fish develop it. If you want to post pictures of the remaining fish, we can check them for diseases.

 

[10 Tanks]

Hello jiji. For one, water changes need to be large and frequent. Weekly water changes of 50 percent is good, but more is always better. If you have water chemistry problems, then a 50 percent water change twice a week isn't too much. You really can't keep large waste producers like Goldfish in such a small tank. I would steadily increase the water changes and add standard aquarium salt to the tank water. A tablespoon for every five gallons of replacement water will help the fish deal with the nitrogen in the water.

10 Tanks (Now 11)

 

[jijifish]

Hi welcome to the forum

Has this tank been set up for long? If you've inherited it from your parents I'd guess so, so it should be a mature filter? When you cleaned it did you clean it with tap water or water from the tank?

Hi, thank you for replying! the tank has been set up for a long time, at least 5 years. When I clean the tank, i used the water from the tank.

If you had ammonia and nitrite readings in the water before the water change it might be good to understand whats going on there - when was the tank last cleaned?

160ppm for nitrates is very high and over time will shorten a fishes life but wouldnt cause a sudden death, black markings on some fish can be caused by nitrates though. Goldfish's colours change so much over time though so its hard to say if that is the issue.

Also just to check which test kit are you using? Is it the dip strips or a liquid kit?

Wills

the tank was last cleaned on the 21st June. I cleaned the sponge filter on the 25th June and I haven't cleaned the other filter yet. I think the last time that was cleaned it was 18th May. I cleaned the one on the right on the 25th June and I haven't cleaned the one on the left (in the photo). I read somewhere that you are meant to rotate in cleaning them both, but the one on the left is making sounds and I'm worried that is full. Is it okay to clean it even though I cleaned the other pump on 25th June? If not, how long should I wait til I have to clean it?

Oh okay, the other fish don't have any black markings yet, so maybe it was the high nitrates.

I am using the API freshwater master test kit liquid with the test tubes.

 

[jijifish]

Have you tested your base water? In some areas of the world the drinking water has a high nitrate. It is unlikely that 160ppm nitrate would out right kill a fish as in the old days people didn't do water changes for years and while fishes do die it would sometime be after many years of ownership. That isn't to say high nitrate is not bad but the effect are more subtle over long period of time - as oppose to nitrite or ammonia which can kill fishes in minutes or hours depending on concentration.
--
Gold fishes are naturally 'dirty' fishes and i doubt your nitrate level had an immediate effect on the fish.

Hi, thank you for replying!

Ohh, okay.. nitrate is a slow killer. Do you think that could be the reason why it the fish died five days later after I did the water change? Okay, I will check the base water.

 

[jijifish]

Check the tap water for ammonia, nitrite and nitrate.

If the tank hasn't been cleaned for a month or more before you took over, then do a 20% water change and gravel clean the substrate every day for a week. Then do a 30% water change and gravel clean every day for a week. Then 50% every day for a week. Then do a 75% water change each day until the nitrate is at 0ppm or whatever the tap water is.

If the tank was getting regular water changes before you took over, then do a 75% water change every day until the nitrates are at 0ppm, or at whatever the level is in the tap water. Then do a 75% water change and gravel clean once a week after that.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Hi, thank you for replying!

Oh, okay.. I will test the tap water! the tank hasn't been cleaned for a month before I took over, so I will do the 20%, 30% and 75% each week.

--------------------

re: the black spot. Did you get any pictures of it?
Black spot is uncommon in fish and is normally caused by a parasitic worm.
Black patches can be bruising from chemical burns, which are normally caused by something bad in the water or washing the filter materials/ media under tap water.

I wouldn't worry about the black spot unless more fish develop it. If you want to post pictures of the remaining fish, we can check them for diseases.

I took a picture of it when the fish died.. Okay thank you!, the other fish don't have any black spots so like you said, it might be a chemical burn instead.. I've attached photos of the other fish, do let me know if you need better photos. I tried to take them whilst they weren't moving as much, but it was kind of hard xD

 

[jijifish]

Hello jiji. For one, water changes need to be large and frequent. Weekly water changes of 50 percent is good, but more is always better. If you have water chemistry problems, then a 50 percent water change twice a week isn't too much. You really can't keep large waste producers like Goldfish in such a small tank. I would steadily increase the water changes and add standard aquarium salt to the tank water. A tablespoon for every five gallons of replacement water will help the fish deal with the nitrogen in the water.

10 Tanks (Now 11)

Hi, thank you for replying!

Okay, I will keep doing water changes! standard aquarium salt? any product recommedations or brands that you suggest?

 

[Colin_T]

The fish look reasonably well. One of the small Koi carp has a milky white edge to the tail, which is due to the water quality and should go when conditions improve. You don't need to add salt to the tank, just do water changes to get the water back in shape.

You have a number of Koi carp in the tank, along with a shubunkin, a common goldfish and a comet goldfish. The Koi have the whiskers on the bottom jaw, goldfish don't have whiskers. Koi carp can reach 3 feet plus and really need a big pond. Your call, just throwing it out there.

The fish with the hole in the belly had an infection inside and it came through the skin. It's not an issue and sometimes happens. If more fish die from the same symptoms then you get them necropsied (animal autopsy) buy a fish vet. But you don't need to treat the tank for anything at this stage. Just do water changes to get the nitrate as close to 0ppm as possible.

 

[anewbie]

Hi, thank you for replying!

Ohh, okay.. nitrate is a slow killer. Do you think that could be the reason why it the fish died five days later after I did the water change? Okay, I will check the base water.

Slow as in months and years; esp for a gold fish; there are some fishes that are more sensitive and must have have very clean/pure water but a gold fish is not one of them. However a sudden change in water parameters is never healthy.

 

[jijifish]

The fish look reasonably well. One of the small Koi carp has a milky white edge to the tail, which is due to the water quality and should go when conditions improve. You don't need to add salt to the tank, just do water changes to get the water back in shape.

You have a number of Koi carp in the tank, along with a shubunkin, a common goldfish and a comet goldfish. The Koi have the whiskers on the bottom jaw, goldfish don't have whiskers. Koi carp can reach 3 feet plus and really need a big pond. Your call, just throwing it out there.

The fish with the hole in the belly had an infection inside and it came through the skin. It's not an issue and sometimes happens. If more fish die from the same symptoms then you get them necropsied (animal autopsy) buy a fish vet. But you don't need to treat the tank for anything at this stage. Just do water changes to get the nitrate as close to 0ppm as possible.

oh okay, thank you for replying! I'll keep doing water changes. thanks for identifying the fish, I have no clue what species these are.. now, I know okay, i will wait and see if any of the other fish show any symptoms and just keep doing water changes for now..

 

[jijifish]

Slow as in months and years; esp for a gold fish; there are some fishes that are more sensitive and must have have very clean/pure water but a gold fish is not one of them. However a sudden change in water parameters is never healthy

thank you for replying!, ahh okay.. that makes sense

 

[anewbie]

thank you for replying!, ahh okay.. that makes sense

It is important to understand that sudden changes even if water quality improves is not good and can shock (kill) the fish.

 

[Byron]

I'll perhaps clarify this a bit, as it is a discussion I had with Neale Monks. First, we need to be clear as to what water parameters are, as opposed to water conditions. Parameeters being GH, KH, pH and temperature cannot have sudden and drastic changes, most of the tie, though there is some variability depending what parameter it is and the fish. But water conditions which are ammonia, nitrite and nitrate should absolutely never be allowed to continue and nitrate should always be lowered as fast and as much as possible. These three are poison, and it is like someone being locked in a closed garage with the car engine idling--you do not go slow, but immediate to get rid of the poison. Fish will not be harmed doing this.

@jijifish we still do not have the test readings for your tap water, especially nitrate. Nitrates occurring partially in the tap water are handled differently from those accruing solely from the biological system. The latter are easier to deal with and lower. And 160ppm is in time deadly; the fish are being weakened the longer these persist, and this makes the fish more susceptible to other issues it can no longer deal with due to the weakened immune system and weakened physiology.