We’ve all been there. I did a huge water change and left the tank clean for the fish. The next day, the fish were dropping like flies.
Sometimes even the best intentions can backfire in unexpected ways. It’s even more true when we do a water change.
It’s possible to perform a water change every week and it will still be difficult.
This article will explain how to save your fish from dying during a water change, and how to avoid this painful experience in the future.
How To Save Dying Fish After Water Change?
You should immediately intervene if your fish behaves strangely after a water change. You should immediately intervene if your fish starts to gasp for air. High ammonia levels can cause fish to sit at the bottom if their fins are tightened.
If you notice the fish shaking, rolling on its back, or losing its buoyancy, this could be due to excessive chlorine levels in the tank.
These are the steps to take in order to save dying fish following water change.
- Check the water temp
- Test pH levels
- Test ammonia levels
- Test nitrite levels
- Chlorinate water
- Check out the air pump
Here are a few recommendations for products that you might need to save a dying fish. The API Freshwater Master Kit (liquid based) is essential.
Do not waste your money and time on inexact or expensive strips. Below is a link to the master kit.
It measures 5 water parameters.
- pH
- High range pH
- Ammoniaque
- Nitrite
- Nitrate
Here’s a quick overview of water parameters that are suitable for saltwater and freshwater aquariums.
Freshwater Parameters
| Parameter | Freshwater | African Cichlid | Brackish |
| Temperature | 72 – 82degF | 72 – 82degF | 72 – 82degF |
| pH | 6.5 – 7.5 | 7.8 – 8.5 | 7.5 – 8.4 |
| Ammonia | 0.0 | 0.0 | 0.0 |
| Nitrite | 0.0 | 0.0 | 0.0 |
| Nitrate | 50 ppm | 50 ppm | 50 ppm |
| Carbonate Hardness | 4-8 KH | 10-18 KH | 10-18 KH |
| General Hardness | 4-12 GH | 12-20 GH | 12-20 GH |
Marine Parameters
| Parameter | Recommended Level: Reef Aquarium | Recommended Level: FOWLR Aquarium | Average Level: Coral Reefs |
| Specific Gravity | 1.023 – 1.025 | 1.020 – 1.025 | 1.025 |
| Temperature | 72 – 78degF | 72 – 78degF | 82degF |
| pH | 8.1 – 8.4 | 8.1 – 8.4 | 8.0 – 8.5 |
| Alkalinity | 8-12 dKH | 8-12 dKH | 6-8 dKH |
| Ammonia (NH3) | Undetectable | Undetectable | Near Zero |
| Nitrite (NO2) | Undetectable | Undetectable | Near Zero |
| Nitrate – Nitrogen (NO3) | 1.0ppm | 30 ppm | 0.25 ppm |
| Phosphate (4 PO4) | 0.2% ppm | 1.0ppm | 0.13 ppm |
| Calcium | 350-450 ppm | 350-450 ppm | 380 -420 ppm |
| Magnesium | 1250 – 1350ppm | 1150 – 1350 PPM | 1300 ppm |
| Iodine | 0.06 – 0.10ppm | 0.04 – 0.10ppm | 0.06 ppm |
| Strontium | 8-14 ppm | 4-10 ppm | 8-10 ppm |
Check the Water Temperature
If your fish becomes stressed after a water change, you must first check the water temperature. The oxygen levels in the tank will drop if it is too hot and the fish may become suffocated.
The fish will then either move to the tank’s bottom for oxygen or to the surface to get some air.
It could also be due to cold water. Cold water can cause fish to become sluggish and weaken their immunity, which in turn will eventually lead to acute stress and diseases.
You should not suddenly change the water temperature. This will cause shock to your fish.
Ice cubes and packs are not recommended for cooling the water. They can cause dramatic results very quickly.
Place a fan in a place where it blows directly on the water. The room’s air conditioner can also be used. You can also reduce the temperature by turning off the tank lights, keeping the room out of direct sunlight, and taking down the tank’s covers if necessary.
You can, however, rely on your heater to slowly increase the temperature.
If there is a power outage, you can use a warm plastic container. Heating pads can quickly increase water temperature, so I don’t recommend them.
Test The pH Levels
When we do a water change, almost all the time it causes a pH imbalance in the tank. Sometimes it is not noticed and has no repercussions. Sometimes, however, it becomes a problem and you have to type questions like “How do I save dying fish after a change in water?”
Too acidic water can cause eye damage, hyperplasia (thickening and skin thickening), skin burns and labored breathing. A fish that lives in an acidic environment will produce excess mucus to defend itself against a high acidic environment.
However, fish can be damaged if the water is too acidic. Also, the outer surfaces of the fish’s gills and skin will be affected. The fish will also become unable to eliminate metabolic wastes.
If you don’t take correct steps, both an acidic or alkaline environment can effectively kill fish.
Reverse osmosis water (RO) or deionized water (DI), can be used to achieve the desired pH. However, it is important to make sure that the water you add to the tank has been tested for pH.
To lower the pH, you can add driftwood to your tank or peat moss to your filter.
You can also use crushed coral gravel or dolomite to increase the pH. These can be used as substrates but you don’t have to use them. You can also fill a mesh bag with crushed coral or dolomite and place it in your filter.
You can also decorate your tank with limestone and coral rocks.
Test The Ammonia Levels
Ironically, sometimes the water change that we do to remove ammonia can come back to bite our backs! If you have destroyed beneficial bacteria in your tank, this can happen.
If that happens, your tank can become a pool of toxic waste regardless of how clean it appears.
Ammonia poisoning is most commonly seen in fish.
- Torn and jagged fins
- Flashing and clamping
- Red streaks on the body, and fins
- Red or lilac gills
- Labored breathing
- Appetite loss
- Lethargy
Two parts of the ammonia buildup are addressed by beneficial bacteria. The first is Nitrosomonas, which oxidizes extremely poisonous ammonia into mildly toxic nitrite.
The second species, Nitrobacter, then oxidizes the nitrite to almost harmless nitrate.
There are products available that can help you to add beneficial bacteria back into your tank and speed up the cycle.
These links will remain mine.
Tetra SafeStart Plus (Freshwater Aquariums)
Instant Ocean BIO-Spira
Sorry to spam you with links. Here’s another link for Fluval Ammonia Removal Filter Pads I found really useful.
It is a natural ion exchange media that works by removing poisonous ammonia from water as it passes through it.
Test Nitrite Levels
Ammonia poisoning almost always comes with nitrite poisoning. Even small amounts of nitrite can cause damage to the immune system in fish.
They are more susceptible to secondary infections like fin rot, ich and bacterial infection. The methemoglobin level also increases, which has a direct impact on blood cells, livers, and gills.
These are the most frequent signs of Nitrite poisoning:
- Brown gills
- Rapid gill movement
- Panting
- Near the water outlet
- Lethargy
A water change is the best way to get rid of nitrite. It wouldn’t be a good idea to repeat the water change if your fish has already been stressed by the initial one.
You can instead reduce the amount of food and increase the aeration. You can also use any of the many online nitrite-removing products if the test kit reveals that nitrite is the cause.
This is the API Nitra-Zorb link I use to maintain my freshwater tanks.
It eliminates all three – nitrate and nitrite – from your tank.
Dechlorinate The Water
It could lead to the death of your fish if you forget to dechlorinate enough or don’t do it properly. The chlorine content in tap water can fluctuate depending upon where you are from. However, it is usually between 0.5 to 2.0 parts per million (ppm).
Chlorotoxicemia can be fatal if it is not treated promptly.
This is because chlorine destroys living cells, resulting in damage of the sensitive scales and gills. Fish that are exposed to chlorine longer periods of time can develop respiratory diseases and even suffocate to death.
To test for chlorine levels in water, you can easily use an online chlorine strip test. If you detect any chlorine, remove the fish immediately.
Since I dechlorinate my water before I test it for chlorine, I have never needed to test my tank.
This is the only decent kit that I could find on Amazon for testing chlorine in aquariums. I believe the only problem is that the instructions are in German. You might be able to use Google Translate to translate them.
Here are some symptoms of chlorine poisoning in fish
- Panting
- Paleness
- Mucus covers the body
- Redness in various parts
- At the surface, gasping for air
- Swimming erratically
Here is a link to the water conditioner from Seachem I use for my tanks.
It can be used for freshwater as well as saltwater tanks.
For 50 gallons (200 Liters) of water, you will need 1 capful (5ml). You should read the instructions as you are really going with the flow when dealing with fish and chlorine.
Check The Air Pump
Also, ensure that the fish have access to oxygenated water and an air pump that works well.
The fish will lose appetite if the pump malfunctions or turns off. As the oxygen level drops further, the fish will experience labored breathing, rapid gill movements, and a desperate attempt to inhale oxygen through more water passing over its gills.
To be safe, add an airstone to your tank if you feel the pump isn’t performing its task properly.
These are my top 6 tips for dealing with fish that are acting strangely or sick after a water change.
Before you sign off, let’s take a look at what can go wrong with water changes.
What Goes Wrong During Water Change?
Can water change cause fish to die? Both yes and no. Water changes aren’t necessarily bad. In fact, they’re extremely important. However, water changes can be difficult and even veterans may have trouble with it.
Ironically, super-clean water is more likely to kill your fish than water contaminated with bacteria and pathogens.
It is true that the water chemistry slowly changes over time due to the fish waste, leftover foods, and leaves. These changes are gradual and fish adapt to them.
When you do a large water change, it causes such drastic changes in the water parameters that fish can’t tolerate them and eventually die. Those who don’t succumb immediately to the change will become extremely stressed and may eventually develop secondary diseases that could prove fatal.
Large water changes usually include more than 60 water changing, cleaning the filter media and rinsing gravel.
So, Should We Stop Performing Water Changes?
No! Water changes should not be stopped. Regular water changes are crucial for your fish’s health and longevity.
Water changes are essential to ensure that the dissolved waste does not build up and pollute the water. This will cause stress to the fish, which can lead to secondary illnesses.
Start small if your fish aren’t responding to water changes well.
Begin by changing less than 5 percent of your total water volume. You can make another water change after a week. Keep going for several more weeks, increasing your water change percentage each week.
Your fish will be able to adjust to new water easily without any shock or harm.
These are some tips to help you water change the next time.
- Do not clean the filter and the gravel at the same time.
- Do not perform large water changes at random.
- Only clean the filter 2 days after water changes.
- The filter should be cleaned every 4-6 weeks. Don’t overdo it.
- Keep your fish in the tank between 20-50% water changes
Final Words: How To Save Dying Fish After Water Change?
If your fish does not respond well to water changes, and you don’t take the correct steps to solve the problem, it could be dead in hours.
Water changes can lead to many problems, including a sudden temperature rise, decreased oxygen levels, impaired pH levels, and an increase in ammonia or nitrate from the elimination of beneficial bacteria.
You should adjust the temperature gradually to achieve the desired setting. Also, make sure to check the levels of nitrate and nitrite in the tank.
It can be overwhelming to run multiple tests on a fish that is suffering. But it is essential that you find the cause of the pain in the fish and take action.
Happy fishkeeping!