Why Are My Fish Staying at Bottom of Tank After Water Change?

Why Are My Fish Staying at the bottom of Tank After Water Change? 

Why Are My Fish Staying at the bottom of Tank After Water Change? 

After a water change, the fish could die if it remains at the bottom of the tank or swims erratically. Even while water changes are crucial, it’s vital to remember that done incorrectly; they can cause problems that could even result in your fish’s death.

Whether you are starting a new fish tank or changing the water in your current tank, you want to make sure that you follow all the proper steps. This will help prevent your fish from staying at the bottom of the tank. There are a few different reasons your fish might stay at the bottom of your tank. These include osmotic shock, chlorine poisoning, and stress.

Osmotic shock

During a water change, some fish may suffer from osmotic shock. This can result in the swelling of organs. As a result, the fish may be unable to move, swim, or eat.

Osmotic shock is a condition that happens when the fish’s body does not regulate the intake and release of ions. It can also happen if a fish’s body cannot control its temperature. In addition to these conditions, a fish can also suffer from various diseases.

Many different ions control the osmotic pressure of water in an aquarium. These are found in the fish’s skin and gills. The ions regulate the water’s salinity, pH, and temperature.

Water changes can disrupt the regulation of ions and the fish’s body temperature. The fish can adapt to the change gradually. But if the change is too drastic, the fish may suffer from osmotic and thermal shock. These changes can also cause the fish to lose its color.

A fish can undergo osmotic shock when the amount of ions in the water changes abruptly. This can result in damage to the fish’s gills and bladder. The fish may also have difficulty breathing. It may also suffer from gill inflammation or skin burns.

There are a variety of ways to prevent osmotic shock. One way is to add a bacteria-starting supplement to the tank. Another way is to decrease the salinity of the water. This is a way to help the fish survive the shock.

If your fish seems in shock, you should try to save them. Osmotic shock is a life-threatening condition. However, fish can be saved if you act quickly. You can also try to acclimate your fish by floating it in a water bag for 20 minutes.

After a water change, you should check your tank’s pH. It would help if you aimed for a difference of about half a point. You can also test the chlorine levels in the water with a chlorine meter.

You can also use a kitchen roll on the water’s surface to remove surface scum. However, chlorine compounds are known to destroy living cells, so you should be careful.


One of the most important factors to consider when keeping fish is keeping an eye on water and parameters. If you notice unusual behavior from your fish, it may be a sign of parasites. In most cases, parasites can be treated with ease.

Parasites are tiny organisms that live in the fish’s body. They feed on the body’s cells and fluids. They can be present in small numbers or large numbers. Some are species-specific, while others are opportunistic. They can be found on the aquarium substrate or floating in the water. Therefore, keeping an eye on water and fish parameters is essential, and preventive measures should be part of your daily routine.

In some cases, a lack of appetite can be a sign of parasites. Fish that aren’t eating may have a weak immune system, which can lead to fungal and bacterial infections. You should check water temperature, pH, and other parameters to see if your fish are sick.

Using salt solutions can be a quick antiparasitic treatment. You can add 30 teaspoons of salt per gallon of water to your tank. You’ll need to do this at least three times a day. You should also perform a 30% to 70% water change between treatments.

It would help if you also kept in mind that many parasites are species specific. That is, they only appear in certain fish. In addition, they can be transmitted from one fish to another. Therefore, you should quarantine any new fish you buy to ensure they don’t spread the parasites to other fish.

Some parasites can be difficult to remove. These include ich, which can be visible as white spots on your fish. The ich life cycle can be as short as 3 to 4 days, depending on the temperature of your aquarium. Treating the fish in their early stages is essential because they have a better chance of survival. You can use antiprotozoal medications or velvet remedies.

Other parasites include fish lice, which wild fish introduce. These organisms spread bacteria and viruses to other fish in your aquarium. You should check with your veterinarian to determine which type of parasites your fish may have. You should also keep a minimum stock of chemicals and parasite killers in your tank.

Chlorine poisoning

Occasionally, hobbyists report that their fish have died after a water change. This can be due to thermal shock or bacterial infection. Regardless of the cause, it is a severe problem.

When a change in water causes osmotic shock, a massive amount of fish can be killed overnight. This happens when the new water has a different pH, KH, or temperature.

This causes the fish to suffer from respiratory stress. They may gasp for air or exhibit spasms and hyperactivity. If you notice these symptoms, you need to get your fish out of the tank as soon as possible. You also need to keep them away from the source of toxicity.

The best solution for fish poisoned by chlorine is to lower the temperature of the water to 70 degrees. You can also use a large air pump to aerate the water. This will remove the chlorine from the water.

In addition, you need to use a conditioner with sodium thiosulfate. This will neutralize chlorine instantly. In a few hours, the fish will be free of chlorine.

If your fish remain at the bottom of the tank after a water change, you should get them out of the tank as soon as possible. Depending on the level of toxins in the water, you may have to perform a bigger water change.

A few other things you can do include putting a fish net in the tank and scooping out the fish. This is especially important for bottom-dwelling fish.

Another method is to use a dechlorinator. This is the most critical additive you can use for your tap water. It will remove chlorine, nitrates, and other contaminants. It will also promote protective mucus. You should wait at least five minutes before adding new water to the tank. It would be best if you also rinse all equipment before returning.

You should also be aware that copper is a toxic metal that can affect invertebrates. So, it is essential to use plastic or stainless steel containers. You can also use a small adjustable heater to heat water in a container.


Whether you’ve just bought a new aquarium, moved your tank, or drained the old tank, your fish can become stressed. Stress is a natural behavior of fish but can also be a sign of an illness.

If your fish exhibits signs of illness, you’ll need to quarantine it and treat it. Parasites, bacteria, or fungal growth may cause the disease. If you need clarification on which, you’ll need to confirm the presence of these organisms with a test kit.

If you find your fish staying at the bottom of the tank, you’ll need to test the water to determine nitrites and ammonia levels. These substances are toxic in any concentration and can affect how your fish behaves.

Fish can become stressed in various ways, including a sudden change in water chemistry or temperature. Stress can also be caused by overcrowding or improper water conditions. Therefore, it’s a good idea to select fish that are tolerant of stress. You can eliminate stress in your aquarium by maintaining stable water chemistry and adding plants.

Changing your water chemistry is one of the most important things you can do to ensure the health of your fish. You can make this process easy by using an aquatic thermometer and heater to measure the temperature of treated water. You can also test the water by using an aquarium test kit.

If you need to figure out whether your fish is stressed, you can leave it in a dim room for a couple of days. It will stay at the bottom of the tank if it’s stressed. You may also notice that it’s rubbing against gravel and rocks. This indicates that it’s not eating or drinking.

When a fish is stressed, it can become aggressive and clumsy. It may also stop using its front fins. It may wiggle its gills or lock its fins at its sides. It may also scratch its surfaces to relieve itching. It may also display other symptoms, including labored breathing and loss of buoyancy control.

After a water change, why is my fish at the bottom of the tank?

Fish with nitrite and ammonia toxicity have damaged gills, which causes respiratory distress. This might explain why you soon notice your fish gasping and dying at the top or bottom of your new tank soon after a water change.


How are fish that are resting at the bottom of the tank handled?

They can also be bottom sitting due to the water, germs or parasites, stress, or digestive issues. If they are bottom sitting because of the water, this has to be fixed by monitoring the water every day and doing significant water changes until the water is within the required ranges.

How long does it take fish to get used to changing water conditions?

For almost all fish species, the acclimation process should take between 30 minutes and an hour.

Should I be concerned if my fish is near the bottom of the tank?

Nothing to be concerned about. Even Your fish is breathing perfectly well if it is lying at the bottom of the aquarium! These installations are characteristic of the absolute simplest. If there are few to no hiding spots, the bottom of the tank could be the safest area for your fish to relax.

Should I remove my fish when changing the water?

You can take the fish out when you make typical water changes of 10% to 15%. Your fish will endure a great deal of stress because you create more work for yourself than is necessary. In addition, it could result in harm to your body.