Betta Fish Laying at the Bottom of the Tank: Reasons & What to Do

It can be shocking to find your beloved betta fish laying at the bottom of the tank.

A change in your betta’s behavior can and should prompt action from you. It is an indicator that something is wrong in the tank or that your fish is ill.

Some causes are easily correctable, and your fish should recover quickly and completely.

Other reasons are more serious and can result in permanent harm or even death for your fish. In all cases, immediate action is the best course.

Betta fish in a pot on the aquarium bottom

Tank Conditions

Your betta could be showing signs of distress due to conditions in its environment. The following are common causes.

High Water Flow

With those glorious, flowing fins, betta fish are not the strongest swimmers.

If your filter system is producing a strong current, then your bettas may rest on the tank bottom simply because they are tired from fighting the water flow.

What to Do: Reduce the flow slightly and see if that makes a difference.

High Nitrite Levels

If you do not keep on top of tank cleanliness, then nitrite levels can spike. Poor water conditions are the perfect breeding ground for bacteria, fungus, and parasites.

Plus, your fish’s immune system will be weakened by these conditions, making it more susceptible to infection.

Nitrites in your betta tank should be lower than 0.25 ppm. A fish impacted by high levels of nitrites will be lethargic and may breathe rapidly.

You may also notice brown coloration around their gills as the nitrites affect blood circulation.

What to Do: Transfer your fish to a quarantine tank and treat them for any bacterial, fungal, or parasitic infections if they show symptoms.

Completely clean and cycle your main tank before returning your betta, and only return them when they have completed their medication regimen.

Nitrate Poisoning and Nitrate Shock

Your fish naturally produces nitrate as a waste product. Nitrates can also rise if you overstock your tank or overfeed your fish.

If levels build over time, your fish can develop nitrate poisoning. You will notice that fish show symptoms gradually over a few weeks, with one fish first showing signs of illness, then another.

A sudden shift in nitrates, either a rapid increase or decrease, can result in nitrate shock. In the case of nitrate shock, the fish may succumb quickly, usually within 24 hours.

Nitrate levels exceeding 20 ppm can be deadly, and water conditions must be corrected quickly.

If you see a change in your betta’s behavior, such as acting listless, laying on the bottom of the tank, refusing to eat, breathing heavily, swimming erratically, and curling their body, you can suspect nitrate poisoning or nitrate shock.

What to Do: First, test your water and determine the nitrate level. Then, change out approximately 50 percent of the water in small increments over the span of several hours (around five percent every hour or two until you reach 50 percent).

Test the water again. Consider adding a nitrate-removing filter for longer control of chemical levels.

Ammonia Poisoning

A healthy tank has a natural nitrogen cycle: fish wastes and decaying plants release ammonia into the water, where beneficial bacteria break it down.

In an unbalanced tank, ammonia levels can spike significantly. A level equal to 1 ppm or higher is cause for concern.

High levels of ammonia will damage your fish’s gills. Your fish may be breathing heavily or fluttering their gills. They may show a lack of appetite and sit on the tank bottom for extended periods.

Check the gill areas and look for red or purple discoloration, which is a good indication of ammonia poisoning.

In advanced cases, you can see red streaks along their bodies.

Long exposure to high ammonia levels can cause significant tissue damage in sensitive areas, such as around the eyes. This condition can be fatal if tank conditions are not corrected.

What to Do: Test your water using a reliable kit that measures NH3 (ammonia). You want the levels to be at 0 ppm. If they are elevated, first do a partial water change of 50 percent.

Use filtered water or dechlorinate tap water before adding it to the tank, ensuring temperature and pH remain steady as you do so.

Test your water again and continue the cycle until the ammonia levels reach 0 ppm.

Another method is to add a chemical detoxifier, or water conditioner, to the water. There are plenty of options available, just make certain the one you select is suitable to betta tanks.

To keep levels low in the long term, consider adding an ammonia removing filter to your tank.

Water Temperature

Water that is either too hot, too cold, or shifts rapidly can cause your betta to go into temperature shock.

In the case of cold water, your fish will be lethargic and may lay on the bottom of the tank. For overly hot water, your fish may be breathing rapidly and staying near the surface.

What to Do: Invest in a quality water heater and thermometer to keep the temperature consistent. This is especially important in smaller tanks where the conditions can fluctuate rapidly depending on the ambient room temperature.

Make sure that your tank is not located next to a window where sunlight can rapidly heat the water.

Set the temperature at a steady level, anywhere between 76 and 80°F (24 to 26°C). Temperatures consistently below 76°F and above 85°F will harm your betta.


Once you have checked the water parameters and verified that they are within limits, you can examine illness as a potential reason your fish is laying on the tank bottom.

Fungal Infection

If your fish is suffering from a fungal infection, you may notice them laboring to breathe and not moving from one spot.

Check their color. If they appear pale and/or have noticeable fuzzy white patches, then assume a fungal infection.

What to Do: Transfer them immediately to a quarantine tank to avoid infecting other fish in the aquarium.

Give an appropriate dose of anti-fungal medication, either a betta-appropriate commercial medication or aquarium salt (1 Tbs per 5 gallons of water), for at least three days.

Parasitic Infection


One of the most common infections in a home aquarium is ich.

This infection is caused by parasitic protozoans that attach to your fish. These parasites can come from newly introduced/infected fish, plants, decorations, or water.

A fish with ich will develop individual white spots on their fins and body, and you may see them rubbing against objects in the aquarium to relieve the annoyance.

In the process, they can lose scales, become bruised, or develop lacerations. In addition, their energy level will decrease, and they may have trouble breathing.

What to Do: If this is your first time diagnosing ich, you may want to seek confirmation from your veterinarian. The correct diagnosis will help you select the right medicine. Other infections can present similar symptoms, so it is best to be certain.

Do not transfer the infected fish to a quarantine tank. For ich, you must treat the tank, not just the individual fish.

Ich can only be treated at the phase in the protozoan’s life cycle when it is not attached to its host.

Water temperature plays a role in determining the length of the life cycle and thus the length of treatment, but on average, treatment takes around 12 days.

There are a variety of chemical medications available. Make sure the one you use is appropriate for betta fish.

Read and follow the instructions and dosing carefully. Some medications require water changes in between doses.


If your fish has an even, dust-like coating on their scales, they may have velvet.

Also known as gold dust disease or rust, the coating is your fish’s body reacting to infection by an Oödinium parasite.

As with ich, you may notice that your fish has reduced energy, trouble breathing, and bumps or scratches itself against objects to rid itself of the parasite.

In later stages of the disease, your fish may hold its fins close to its body, its eyes may become cloudy or protruding, and they may develop skin ulcers.

What to Do: First, set up a quarantine tank for your betta. Slowly raise the water temperature over a 24-hour period to between 82 and 85°F (27 to 29°C).

Keep the lights off during this period as this parasite can also use photosynthesis. Slowly add one teaspoon of aquarium salt for every gallon of water in the tank over a four-hour period.

If this method is not successful, you can try medications, such as malachite green or copper sulfate.

In these cases, make sure that you only apply them to quarantined fish. Copper is deadly to any invertebrates that may be in your community tank.

Treatment time can take up to four weeks. As with ich, the parasite is only treatable when it is outside of its host. In the water, it can only last two days without a new host.

Bacterial Infection

An injury, stress, or compounding illness can make your betta more susceptible to infection by bacteria naturally present in the tank.

If you notice that your betta is holding their fins close to their body, it may be a sign of bacterial infection.

Likewise, unusual shaking or trembling behavior should be cause for concern.

What to Do: Isolate your sick fish and treat them with an appropriate antibiotic.

Thoroughly clean and cycle the main tank and only return your fish after they have completed the treatment regimen.


While not an illness with one specific cause, dropsy is a visible swelling of a fish’s abdominal area.

It can result from poor diet or water conditions, a primary viral or bacterial infection, old age, or kidney failure.

In severe cases, the swelling results in distention of the scales, which is called pineconing. Your fish will be highly lethargic, have no appetite, and may gasp when breathing.

What to Do: Prepare a quarantine tank with a lower water level, air stone, and heater.

Keep the temperature around 78°F (25°C) and gradually add aquarium salt (one-half teaspoon per gallon of water).

Antibiotics added to the water will help speed recovery. Remember that dropsy can be fatal in the later stages, so early treatment is best.

Swim Bladder Disease

A fish laying on its side may be affected by swim bladder disease.

They may also float near the water’s surface or stay motionless on the tank bottom. When moving, they will struggle, often swimming sideways or even upside down.

This common condition can result from genetics, poor water conditions, diet, or overfeeding.

Your fish cannot regulate its natural buoyancy as bloating or air in their swim bladder impacts their equilibrium.

What to Do: First, determine what is causing the problem. Then, treat it accordingly.

For example, the most common cause, gastrointestinal issues, can be resolved by fasting your fish for three days, then feeding them a blanched pea or daphnia.

Check your water temperature as well. Temperatures that are too low can cause your fish’s digestive system to slow down, which can result in blockage.

Rapid temperature fluctuations can also shock your betta. If this is the case, set the temperature to a steady level and reduce the amount of light in the tank for a few days.

A bacterial or parasitic infection can be treated by isolating the fish in a quarantine tank and giving them the appropriate medication.

Old Age

Bettas have an average lifespan of three to five years. An older fish is more likely to spend increased amounts of time resting on the tank bottom.

What to Do: Nothing. This is not cause for alarm and is just the natural aging process for your fish.

Keeping Your Betta Healthy

No one wants their fish to suffer unnecessarily. There are some simple ways to protect your betta from becoming ill in the first place.

While no method is perfect, if you keep in mind the following, you will provide the best environment for your fish and thereby the best way to protect their health.

Quarantine all New Additions to Your Tank

The easiest way to prevent infection is to keep unwanted organisms out of the tank in the first place.

Many of the infections and illnesses mentioned above can be prevented by the strict quarantine of any new animal, plant, decoration, substrate, or equipment you are planning to introduce.

Keep them isolated for at least two weeks to ensure there are no contaminant pests, parasites, or bacteria.

Check the Water Routinely

If the water conditions are poor, then your fish will be stressed. Stress weakens their immune system and makes them susceptible to infection.

Maintain the water temperature between 76 and 80°F (24 to 26°C). Keep ammonia and nitrite levels at 0 ppm; nitrates should be under 20 ppm.

Invest in a reliable test kit and test your water regularly to ensure these levels remain steady.

Always cycle your tank for a few weeks before adding your fish. Placing fish in an immature tank is a primary cause of ammonia poisoning.

Be careful with medications as some used to treat bacterial infections can kill off the helpful bacteria in your tank, causing a rise in ammonia.

Use an appropriately sized sponge filter system for your tank and clean it regularly.

Vacuum the substrate, clean the decorations, and perform regular water changes. Consider adding an aeration system and live plants to your tank to keep oxygen levels high and nitrates low.

Avoid Overfeeding Your Fish

Proper nutrition will keep your betta in top condition for resisting infection. Feed them a high-quality betta fish food and a decent variety of nutrient sources.

Avoid overfeeding them and only give as much as they can finish in a few minutes (around two to three pellets per day).

Soak any freeze-dried foods in water before feeding them to your betta. Remove all uneaten food as the decaying matter can impact your water quality.

Lower Other Stressors

Any additional stressors can degrade your fish’s immune system. Strive for the most peaceful environment possible for your fish’s optimum health.

Is your betta stressed by other fish in its tank? Is there another male in the tank with which they are fighting? Add live plants to your tank and plenty of hiding spots to lower stress levels.

Is your tank overstocked? Keep within recommended stocking numbers for your size of tank.

Do your fish have enough space? Consider upgrading to a larger tank.

In addition to giving your fish more room, the increased water volume will slow the rapid swing in water parameters that can occur in smaller tanks.

Are the tank mates appropriate? Select tank mates that are compatible with the water parameters needed by your betta fish. You do not want to stress your fish by keeping them at the edges of their tolerance.

Closing Thoughts

We cannot stress enough that the best course of action is prevention. If you follow the tips listed in the section above, you will have the best chance of keeping a happy and healthy betta.

No procedures are foolproof, however, and knowing the signs of infection or water conditions that can cause your betta to lay on the bottom of the tank will guide you to a faster solution.

Join the conversation! What is your routine for maintaining perfect tank conditions for your betta?