Fish dead after water change

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I agree with everyone here somehow you accidentally poisoned your fish. But sounds like you where taking all the precautions to wash and clean your hands and arms, so it wasn't from your person, it had to be something different with your water source.What I think you should start doing is allowing the tap water to set in containers before using it for water changes, I use to use 2 1/2 gallon water containers the ones with spouts on them. Chlorinate the water and let it set for a week between water changes. Go back to doing small water changes and really clean your substrate to help with nitrates. Slowly with each water change increase the amount of water you change, allowing your fish to adjust to the changes in water.
I like that idea. I'll treat the water and let it sit a few days. I'll clean the substrate in thirds since it's going to be tough as I have lots of media in the tank.
 
I have had tanks for years. I use the same clean bucket I always use to change water. I always thourghly wash the bucket out with scalding hot faucet water. I use the bucket for nothing else. I added the water treatment before the water was added. 2/3 in the first bucket. The only thing I did do wrong is not add a full dose to the second bucket but I did add some to that bucket. Then 1/3 total dose in the last bucket. The total dose was more than called for.

From what I have read, chlorine kills fish over a short period of time, not instantly. If some of the chlorine wasn't instantly neutralized it wasn't much. It would not have killed the zebra within 2 mins of me finishing the water change.
Most plastic will leach chemicals if they are exposed to heat. This includes buckets and hot water. Fish buckets should preferably be made from food grade plastic and only washed in cold water.

As plastics get older, they are more likely to leach things into the water.

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If you have ammonia in your tap water, then you have chloramine in your tap water. This is harder to deal with than just chlorine.

Chloramine is a combination of chlorine and ammonia. They bind together and continue to poison and kill stuff for months. It is used by countries with hot climates or where water has to travel long distances because of this feature (it stays poisonous for months and kills things in the water for that time).

If the water company has done work on the pipes, they will increase the chlorine/ chloramine levels to make sure nothing is alive in the water. They don't normally tell you when they are doing work on the pipes and it can happen at any time of the day or night or any time of the year.

eg: There was a burst pipe in my neighbourhood the other day. I didn't know about it until I turned the tap on and brown water came out. I didn't use the tap for a couple of hours after that and when I did use it, the tap water stank of chlorine. We have chlorine not chloramine.

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Chlorine and chloramine will kill fish within seconds to minutes of a poisoning occurring. It depends on how much chlorine/ chloramine the fish is exposed to. If the levels were higher than normal due to work being done on the pipes, or someone made a mistake at the pumping station and they added too much chlorine or ammonia, then the fish can easily be poisoned.

I experienced this first hand many years ago. I used to gravel clean and drain my tanks, then refill them with the hose. I added a double dose of dechlorinator before filling. I did this for years and one day I did it and wiped out an entire tank of fish within a minute of adding the new water. The water company had done work on the pipes and triple dosed with chlorine and I killed every fish in the tank within a minute of adding the new water.

This is why I always state, all new water should be free of chlorine/ chloramine before it is added to an aquarium. You never know when the water company is going to add something extra to the water. So it's better to be safe and spend a few minutes dechlorinating and aerating any new tap water before it gets put in a tank with livestock..

In addition to chlorine/ chloramine killing fish, excess ammonia in the water, caused by the water company making chloramine, will poison fish, especially if the pH of the water is above 7.0, which it normally is because the water companies like the water to have a high pH so the chlorine/ chloramine last longer and so the pipes don't corrode as quickly.
 
This may be a n00b question, but how high do nitrates need to be for the situation to be considered "old tank syndrome"?
High nitrates and Old Tank Syndrome can occur to together or separately.

Nitrates are the end result of the filtration cycle. You normally remove/ dilute nitrates by doing regular water changes and gravel cleaning the substrate.

You want nitrates as close to 0ppm as possible and always under 20ppm.

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Old Tank Syndrome is caused by lack of maintenance on an aquarium. This includes lack of water changes, lack of gravel cleaning, and not cleaning the filter. This causes the pH, KH & GH of the water to drop due to acids in the water; it normally causes the nitrates to go up; and it increases the number of microscopic organisms in the water.

Tanks that are suffering from Old Tank Syndrome (OTS) generally haven't been water changed for more than a month. The pH is usually well below 7.0, and quite often it is below 6.0. I have seen tanks with OTS that have a pH below 4.0 (that was as low as the test kit went). The nitrates can be anywhere from 0ppm to 200+ppm.

If a tank has not had a water change for more than a month, you should do a small 10% water change & gravel clean each day for a week. Then do a 20% water change and gravel clean every day for a week. Then do a 30% water change and gravel clean every day for a week. After that do a 50% every day for a week. Then you can do a 75% water change and gravel clean once a week or once a fortnight.

By doing small water changes and gravel cleans each day and building up the volume over time, you reduce the risk of pH, KH and GH shock, as well as slowly bringing nitrates down. Normally you want nitrates brought down as quickly as possible, but pH and GH shock is a bigger issues, especially pH shock (acidosis or alkalosis). The pH shock can kill fish in hours or days and there is no cure other than putting the fish back into the old water. Even then the stress and damage that occurs to the fish usually kills the fish.
 
This may be a n00b question, but how high do nitrates need to be for the situation to be considered "old tank syndrome"? When I was reading OP's original question my inner monologue was "oh no nitrates were really high and then got halved, that must have shocked the fish", but it doesn't sound like anyone else was thinking along those lines, so I'm just Monday morning quarterbacking this to try and figure out how you guys concluded "other source of poisoning"?
@Colin_T @kwi @Utar
It's not old tank syndrome. Tank is only 2 months since I completely redone the entire tank. Hi nitrates has only recently became an issue. Tank is a bit overstocked. I have a
It can be if too much of a water change was done all at once, look up old tank syndrome
It's not old tank syndrome. Tank is only 2 1/2 months since I set it uoverstocked and I have been neglecting cleaning the substrate. In the 2 months since I put fish in, I have cleaned 1/3 of of the substrate. It's apparent the substrate needs cleaned more often.
Most plastic will leach chemicals if they are exposed to heat. This includes buckets and hot water. Fish buckets should preferably be made from food grade plastic and only washed in cold water.

As plastics get older, they are more likely to leach things into the water.

-------------------
If you have ammonia in your tap water, then you have chloramine in your tap water. This is harder to deal with than just chlorine.

Chloramine is a combination of chlorine and ammonia. They bind together and continue to poison and kill stuff for months. It is used by countries with hot climates or where water has to travel long distances because of this feature (it stays poisonous for months and kills things in the water for that time).

If the water company has done work on the pipes, they will increase the chlorine/ chloramine levels to make sure nothing is alive in the water. They don't normally tell you when they are doing work on the pipes and it can happen at any time of the day or night or any time of the year.

eg: There was a burst pipe in my neighbourhood the other day. I didn't know about it until I turned the tap on and brown water came out. I didn't use the tap for a couple of hours after that and when I did use it, the tap water stank of chlorine. We have chlorine not chloramine.

-------------------
Chlorine and chloramine will kill fish within seconds to minutes of a poisoning occurring. It depends on how much chlorine/ chloramine the fish is exposed to. If the levels were higher than normal due to work being done on the pipes, or someone made a mistake at the pumping station and they added too much chlorine or ammonia, then the fish can easily be poisoned.

I experienced this first hand many years ago. I used to gravel clean and drain my tanks, then refill them with the hose. I added a double dose of dechlorinator before filling. I did this for years and one day I did it and wiped out an entire tank of fish within a minute of adding the new water. The water company had done work on the pipes and triple dosed with chlorine and I killed every fish in the tank within a minute of adding the new water.

This is why I always state, all new water should be free of chlorine/ chloramine before it is added to an aquarium. You never know when the water company is going to add something extra to the water. So it's better to be safe and spend a few minutes dechlorinating and aerating any new tap water before it gets put in a tank with livestock..

In addition to chlorine/ chloramine killing fish, excess ammonia in the water, caused by the water company making chloramine, will poison fish, especially if the pH of the water is above 7.0, which it normally is because the water companies like the water to have a high pH so the chlorine/ chloramine last longer and so the pipes don't corrode as quickly.

Most plastic will leach chemicals if they are exposed to heat. This includes buckets and hot water. Fish buckets should preferably be made from food grade plastic and only washed in cold water.

As plastics get older, they are more likely to leach things into the water.

-------------------
If you have ammonia in your tap water, then you have chloramine in your tap water. This is harder to deal with than just chlorine.

Chloramine is a combination of chlorine and ammonia. They bind together and continue to poison and kill stuff for months. It is used by countries with hot climates or where water has to travel long distances because of this feature (it stays poisonous for months and kills things in the water for that time).

If the water company has done work on the pipes, they will increase the chlorine/ chloramine levels to make sure nothing is alive in the water. They don't normally tell you when they are doing work on the pipes and it can happen at any time of the day or night or any time of the year.

eg: There was a burst pipe in my neighbourhood the other day. I didn't know about it until I turned the tap on and brown water came out. I didn't use the tap for a couple of hours after that and when I did use it, the tap water stank of chlorine. We have chlorine not chloramine.

-------------------
Chlorine and chloramine will kill fish within seconds to minutes of a poisoning occurring. It depends on how much chlorine/ chloramine the fish is exposed to. If the levels were higher than normal due to work being done on the pipes, or someone made a mistake at the pumping station and they added too much chlorine or ammonia, then the fish can easily be poisoned.

I experienced this first hand many years ago. I used to gravel clean and drain my tanks, then refill them with the hose. I added a double dose of dechlorinator before filling. I did this for years and one day I did it and wiped out an entire tank of fish within a minute of adding the new water. The water company had done work on the pipes and triple dosed with chlorine and I killed every fish in the tank within a minute of adding the new water.

This is why I always state, all new water should be free of chlorine/ chloramine before it is added to an aquarium. You never know when the water company is going to add something extra to the water. So it's better to be safe and spend a few minutes dechlorinating and aerating any new tap water before it gets put in a tank with livestock..

In addition to chlorine/ chloramine killing fish, excess ammonia in the water, caused by the water company making chloramine, will poison fish, especially if the pH of the water is above 7.0, which it normally is because the water companies like the water to have a high pH so the chlorine/ chloramine last longer and so the pipes don't corrode as quickly.
Very Good points. I will be changing from the cheap tetra stuf to Seachems Prime water conditioner as it deals with chlorine, chloramine and naturalizes ammonia with stress coat. I'm will also let it sit and areate a while before adding it. It's amazing how lucky I have been since I started 10 years ago. Lost a lot of fish along the way too but I'm learning everyday. I'm also dealing with my dad's tanks as he would rarely clean it maybe 2 - 3 times a year. I've started cleaning it for him every week cuz I know he won't do it. It's okay though, I really enjoy fish keeping
 
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It's not old tank syndrome. Tank is only 2 months since I completely redone the entire tank. Hi nitrates has only recently became an issue. Tank is a bit overstocked. I have a

It's not old tank syndrome. Tank is only 2 1/2 months since I set it uoverstocked and I have been neglecting cleaning the substrate. In the 2 months since I put fish in, I have cleaned 1/3 of of the substrate. It's apparent the substrate needs cleaned more often.

Highly doubt it's chlo

Very Good points. I will be changing from the cheap tetra stuf to Seachems Prime water conditioner as it deals with chlorine, chloramine and naturalizes ammonia with stress coat. I'm will also let it sit and areate a while before adding it. It's amazing how lucky I have been since I started 10 years ago. Lost a lot of fish along the way too but I'm learning everyday. I'm also dealing with my dad's tanks as he would rarely clean it maybe 2 - 3 times a year. I've started cleaning it for him every week cuz I know he won't do it. It's okay though, I really enjoy fish keeping
 
It's not old tank syndrome. Tank is only 2 1/2 months since I set it uoverstocked and I have been neglecting cleaning the substrate. In the 2 months since I put fish in, I have cleaned 1/3 of of the substrate. It's apparent the substrate needs cleaned more often.

Very Good points. I will be changing from the cheap tetra stuf to Seachems Prime water conditioner as it deals with chlorine, chloramine and naturalizes ammonia with stress coat. I'm will also let it sit and areate a while before adding it. It's amazing how lucky I have been since I started 10 years ago. Lost a lot of fish along the way too but I'm learning everyday. I'm also dealing with my dad's tanks as he would rarely clean it maybe 2 - 3 times a year. I've started cleaning it for him every week cuz I know he won't do it. It's okay though, I really enjoy fish keeping
You want to try and gravel clean as much of the substrate as possible, any time you do a water change. The only time you don't clean the gravel is if there are live plants in the tank. Then you gravel clean around the plants but leave the substrate where the plants are, and leave an inch of undisturbed gravel around each plant.

Lots of people get lucky with fish and in particular doing water changes by adding dechlorinator to the tank and filling it with tap water. Sometimes they go through their entire lives not losing a fish to tap water, but most people eventually go through this issue or know someone who does. We have had a few on here in the last couple of months with exactly the same issue (chlorine/ chloramine poisoning). They do a water change and minutes later the fish are gasping at the surface and dropping dead all over the tank. It's happened to me and numerous people I know and will continue to happen. It's a matter of trying to reduce the risks to the fish by dechlorinating tap water before it goes into an aquarium with fish, shrimp, snails or other living things.
 
It's not old tank syndrome. Tank is only 2 months since I completely redone the entire tank. Hi nitrates has only recently became an issue. Tank is a bit overstocked. I have a

It's not old tank syndrome. Tank is only 2 1/2 months since I set it uoverstocked and I have been neglecting cleaning the substrate. In the 2 months since I put fish in, I have cleaned 1/3 of of the substrate. It's apparent the substrate needs cleaned more often.



Very Good points. I will be changing from the cheap tetra stuf to Seachems Prime water conditioner as it deals with chlorine, chloramine and naturalizes ammonia with stress coat. I'm will also let it sit and areate a while before adding it. It's amazing how lucky I have been since I started 10 years ago. Lost a lot of fish along the way too but I'm learning everyday. I'm also dealing with my dad's tanks as he would rarely clean it maybe 2 - 3 times a year. I've started cleaning it for him every week cuz I know he won't do it. It's okay though, I really enjoy fish keeping
How often should I clean/change the filter media? The way I always cleaned the media was to swish it in a bucket of old tank water. But I rarely change it. Maybe 2 times a year. Should I clean it more often? How often should I clean the filter itself? Last thing I want to do is disrupt the good bacteria. Anytime I do change the filter I seed it with pieces of old filter. Is this really needed is an established tank? And how often should vaccume the substrate? I know a lot of good bacteria live there as well
 
This may be a n00b question, but how high do nitrates need to be for the situation to be considered "old tank syndrome"? When I was reading OP's original question my inner monologue was "oh no nitrates were really high and then got halved, that must have shocked the fish", but it doesn't sound like anyone else was thinking along those lines, so I'm just Monday morning quarterbacking this to try and figure out how you guys concluded "other source of poisoning"?
@Colin_T @kwi @Utar
OTS could be an issue, not one we usually go to in a 2 month old tank but certainly not improbable.
 
The larger the water changes the more likely you are going to have problems. That is why I always say just 25% once a week.
 
How often should I clean/change the filter media?
Established filters should be cleaned at least once a month and every 2 weeks is better.

New filters should not be cleaned until at least 2 weeks after they have finished cycling (usually around 6-8 weeks old). If you clean new filters too soon, the beneficial filter bacteria can get washed off the media and you have to start the cycling process from the beginning.

Wash filter media/ materials in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the lawn.

Filter media should only be replaced when it starts to fall apart. If you have filter pads/ cartridges, add some sponges to the filter and after a few months, you can throw the pads/ cartridges away and don't bother replacing them.
 
You want to try and gravel clean as much of the substrate as possible, any time you do a water change. The only time you don't clean the gravel is if there are live plants in the tank. Then you gravel clean around the plants but leave the substrate where the plants are, and leave an inch of undisturbed gravel around each plant.

Lots of people get lucky with fish and in particular doing water changes by adding dechlorinator to the tank and filling it with tap water. Sometimes they go through their entire lives not losing a fish to tap water, but most people eventually go through this issue or know someone who does. We have had a few on here in the last couple of months with exactly the same issue (chlorine/ chloramine poisoning). They do a water change and minutes later the fish are gasping at the surface and dropping dead all over the tank. It's happened to me and numerous people I know and will continue to happen. It's a matter of trying to reduce the risks to the fish by dechlorinating tap water before it goes into an aquarium with fish, shrimp, snails or other living things.

I am going to be using a Python water changer soon. Both tanks have only just finished cycling, both have live plants so am going to do the big water change before adding fish (giving the live plants a treat with the high nitrates). Do I dose directly into the tank my the water outlet on the python? I am using Prime so willl be dosing for the whole tank and not just the water I am replacing
 
I don't use Python gravel cleaners because they fill the tank with chlorinated tap water and this is what caused the initial problem. I just use a gravel cleaner with a long hose and gravel clean the tank water out the door onto the lawn. Then I have holding tanks with tap water that is aerated and dechlorinated and made up ready to go back in the tanks. I use a small water pump to pump this treated water into the tanks via a hose. You could do similar and use a plastic bin/ storage container filled with tap water, then dechlorinated and aerated for 30 minutes. Then use a small water pump to fill the tanks with that water.
 

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