Water changes are essential in the majority of tank setups and they have to be done to simply maintain steady water parameters and help to counter the ammonia cycle in the tank.
Although the actual process of a water change in an aquarium is generally very streight forward, we have noticed a number of people reaching out with various questions about why their fish are swimming at the top of their tank after a water change.
This can actually be due to a number of reasons with some of them being very easy to avoid if you prepair for your water change correctly.
In addition to that, some of the reasons can also be fatal to fish if they are not corrected quickly enough so we wanted to publish our own article going over the topic.
Is It Normal For Fish To Swim At The Top Of The Tank After A Water Change?
Some of the reasons that your fish may swim at the top of their tank after a water change can be considered natural and normal but other issues can often be avoided if you do your water change correctly.
The effects of the water chance can be minimised by implimenting a smaller water change of between 10% and 30% of the water rather than water changes that are 50% or more.
In many cases, simply reducing the amount of water that you change in your tank at any given time will be able to fix the majority of problems we see people having after a water change so keep that in mind as a quick and easy fix!
Why Do Fish Swim At The Top Of The Tank After A Water Change?
We have some bullet points below going over a quick summary of the more common problems that can cause your fish to swim at the top of their tank after a water change but we will cover them all in detail throughout the article!
- A Rapid Change In Water Parameters!
- You Changed Too Much Water!
- Water Temperature Changes!
- O2 Levels Depleated!
- Chlorine In The New Water!
- You Removed The Beneficial Bacteria From The Substrate Or Filter Media!
- Your Tap Water Has High Levels Of Saturated Gas!
A Rapid Change In Water Parameters!
One of the more common reasons that your fish may swim to the top of their tank after a water change is due to a rapid change in one or more of the water parameters.
This is often caused by not using an aquarium water conditioner when you add new water to your tank which can lead to a sudden change in things like pH, hardness and chlorine levels.
If you have multiple aquariums you can sometimes plan your water changes so you can use water from your larger tanks as the fresh water for your smaller tanks to reduce the amount of parameters that your water change effects at once helping your fish adjust easier.
You Changed Too Much Water!
Another very common reason that your fish may be swimming to the top of their tank after a water change is because you changed too much water at once.
As we mentioned above, it is often best to do smaller water changes on a more frequent basis rather than large water changes less often.
This is because large water changes can often lead to a rapid change in water parameters as we discussed above which can be very stressful on your fish.
Water Temperature Changes!
One of the most common problems that we see people having after a water change is due to a sudden change in water temperature.
This can happen if the new water you are adding to your tank is either too cold or too hot when compared to the current temperature of the water in your aquarium.
The sudden change in temperature can often lead to your fish becoming very stressed which can cause a number of problems including swimming to the top of their tank.
To avoid this, it is always best to use an aquarium water heater to slowly raise the temperature of the new water to match that of your aquarium before adding it in.
O2 Levels Depleated!
Another common reason that your fish may swim to the top of their tank after a water change is because the oxygen levels in the water have become depleted.
This can often happen if you do not aerate your aquarium well enough or if you have too many fish in your tank which can lead to a decrease in the amount of oxygen dissolved in the water.
To avoid this, it is always best to use an aquarium air pump and stone to aerate your aquarium well and to make sure you do not overstock your tank.
Chlorine In The New Water!
One of the most common problems that we see people having after a water change is due to the chlorine in their tap water.
Chlorine is often used by municipalities to disinfect tap water but it can be very harmful to fish if it is not removed before adding new water to your tank.
The best way to remove chlorine from your tap water is to use an aquarium water conditioner that is specifically designed to remove it.
You Removed The Beneficial Bacteria From The Substrate Or Filter Media!
Another common problem that can occur after a water change is if you removed the beneficial bacteria from your substrate or filter media when you cleaned it.
These bacteria are responsible for breaking down the waste in your aquarium and if they are removed, it can often lead to an increase in ammonia levels which can be very harmful to your fish.
To avoid this, it is always best to use an aquarium vacuum cleaner that has a bacteria safe hose or to simply rinse your substrate and filter media in old aquarium water to remove the waste without removing the beneficial bacteria.
You Didn’t Add Enough New Water!
One of the most common problems we see people having after a water change is that they simply didn’t add enough new water to their tank.
This can often lead to a decrease in the overall volume of water in your aquarium which can be very stressful on your fish.
To avoid this, it is always best to add at least 10-20% of the total volume of your aquarium in new water each time you do a water change.
Your Tap Water Has High Levels Of Saturated Gas!
Another common problem that we see people having after a water change is due to the high levels of saturated gas in their tap water.
This can often happen if you live in an area with hard water or if your municipality adds chemicals to the water to disinfect it.
The high levels of saturated gas can often lead to your fish becoming very stressed which can cause a number of problems including swimming to the top of their tank.
To avoid this, it is always best to use an aquarium water conditioner that is specifically designed to remove saturated gas from your tap water before adding it to your aquarium.
How Can I Help Fish Swimming At The Top Of The Tank After A Water Change?
If you notice that your fish are swimming at the top of their tank after a water change, there are a few things you can do to help them.
First, make sure that you are adding new water to your aquarium slowly and carefully so that the temperature of the new water has time to equalize with the existing water in your aquarium.
You should also make sure that you are using an aquarium water conditioner to remove any chlorine or other chemicals from your tap water before adding it to your aquarium.
Finally, if you have removed the substrate or filter media from your aquarium during the water change, make sure to rinse it in old aquarium water before putting it back in your tank.
This will help to ensure that you do not remove the beneficial bacteria that are responsible for breaking down the waste in your aquarium.
How Long Will Fish Swim At The Top Of The Tank After A Water Change?
If you notice that your fish are swimming at the top of their tank after a water change, it is usually because they are stressed from the change in water conditions.
This stress can often cause your fish to swim erratically or hide for a period of time.
The good news is that this stress is usually only temporary and your fish will typically return to their normal behavior within a day or two.
If you are concerned about your fish, make sure to observe them closely and consult your local fish store or veterinarian if you have any further questions.
How Do I Prevent My Fish From Swimming At The Top Of The Tank After A Water Change In The Future?
If you are concerned about your fish swimming at the top of their tank after a water change in the future, there are a few things you can do to prevent it.
First, make sure that you are adding new water to your aquarium slowly and carefully so that the temperature of the new water has time to equalize with the existing water in your aquarium.
You should also make sure that you are using an aquarium water conditioner to remove any chlorine or other chemicals from your tap water before adding it to your aquarium.
Finally, if you have removed the substrate or filter media from your aquarium during the water change, make sure to rinse it in old aquarium water before putting it back in your tank.
This will help to ensure that you do not remove the beneficial bacteria that are responsible for breaking down the waste in your aquarium.
By following these simple tips, you can help to ensure that your fish do not experience stress after a water change and that they remain healthy and happy in their aquarium.
