List of 7 Causes and a List of Easy Treatments for Betta Fin Curling

The disheartening sight of your Betta fish fin curling can be a cause for concern. The curling of your Betta fish (Siamese fighting fish) fins, taking the shape of wilting petals in the sun, is a distress call from your aquatic companion. Unfortunately, the condition can worsen quickly if you don’t take immediate action.

In most cases, Betta fish fin curling results from poor water conditions and nutrition, stress, diseases, aging, and inappropriate swimming. It can also be a result of a genetic anomaly, especially if the betta mother was born with curled fins.

In the rest of this article, I’ll discuss the main reasons why your betta fish fins may be curling. I’ll also cover treatment and prevention options to keep your betta fish safe. Keep reading!

1. Poor Water Conditions

Poor water conditions are the main reason for betta fish fin curling.

Water is essential for any fish’s well-being since it is their habitat and also supplies the needed oxygen. Therefore, maintaining the optimum water conditions for your betta fish will prevent issues like curling fins and other problems.

Aquarists’ main challenge is knowing the correct water parameters for a betta fish. Knowing what betta fish requires in terms of water conditions is the first step in ensuring the right water conditions to prevent fin curling.

Optimum betta fish water conditions are classified into the following:


Temperature affects the amount of oxygen dissolved in water. High aquarium water temperatures lowers the amount of dissolved oxygen the fish needs for survival.

On the other hand, extremely low temperatures lowers the rate of metabolic activities in fish. Your betta fish needs optimal metabolic activities for good health and betta fin posture.

Other consequences of low temperatures for betta fish are:

  • Reduced growth rate
  • Low feeding rates
  • Burst escape speed

The optimal water temperature for a betta fish aquarium is between 24.4°C and 27.7°C.

Apart from using a thermometer to measure the water temperature, you can look for the creation of a bubble nest. Betta fish, especially male ones, create bubble nests in optimal water temperatures.

Betta fish create the most bubble nests at 26.6°C. Therefore, this is the most optimal temperature for these fish that will prevent fin curling.

Also Read: Signs of a Stressed Koi Fish and their Remedies

Ammonia and Nitrite

The presence of ammonia and nitrite in the water is another water condition that contributes to the curling of fins in betta fish.

Ammonia is formed in the aquarium when organic matter and uneaten feed decompose. This process is initiated by the nitrogen cycle, whereby bacteria convert excess food and fish waste into ammonia and nitrite.

Ammonia and nitrite are lethal to betta fish and contribute significantly to the curling fins. High ammonia levels in the aquarium makes it hard for the fish to excrete ammonia from its body, impairing normal functioning.

Besides fin curling, the accumulation of ammonia in a betta fish’s body exposes it to:

  • Internal organ damage
  • Stress
  • Gill damage
  • Death

On the other hand, the presence of nitrites in the water exposes the fish to anoxia as it converts hemoglobin to methemoglobin. Methemoglobin is catastrophic due to its inability to carry oxygen.

You need nitrifying bacteria in the aquarium to convert nitrites into nitrates.

Nitrates are not toxic to fish but still contribute to poor growth and health, such as bent fins in betta fish. You can easily monitor the levels of these compounds by testing your aquarium water on a regular basis. 

The best levels of ammonia and nitrite in a betta aquarium are zero.

pH Levels

Water pH refers to how acidic or basic the water is. pH is measured from 1 to 14, with 7 considered neutral. More acidic water has a lower pH, while the more basic water has higher pH levels.

Water pH is essential in preventing skin diseases, stress, and poor health in betta fish. These are other factors that contribute to curling fins in these fish.

Different fish species prefer different aquatic conditions, including water pH levels. Betta fish thrives in a neutral pH between 6.5 and 8.

A pH lower than 6.5 is acidic and exposes your fish to curling fins. Similarly, a basic pH level exceeding 8 is also unsuitable for your fish as it causes skin irritation and poor health.

Water pH and hardness are related factors that impact the safety of your beta fish. It’s worth noting that water with high levels of dissolved minerals is considered hard and will have a higher pH level. When looking for water hardness, betta fish flourish in 5 to 20 dH. Hard water can curl your betta fish’s fins.

2. Poor Food and Nutrition

Betta fish fin curling
Betta fish fins

Fish food is essential for the well-being of your betta as it supplies the nutrients needed for healthy fins and general health.

Wild bettas are carnivores that feed primarily on mosquito larvae. However, most captive bettas are fed on dry fish food that lacks essential nutrients.

Poor nutrition greatly impacts the health and growth of your betta fish and may lead to fin curling and other health issues.

If you want healthy and happy betta fish, ensure they are fed well with nutritional food for their species. Controlling the amount of food is also vital as this will prevent overfeeding or underfeeding, which may lead to constipation.

Some fish foods to help alleviate curled fins in betta fish include the following:

  • Spirulina/seaweed
  • Salmon and Roe
  • Shrimp
  • Dark leafy greens
  • Paprika
  • Marigold
  • Cyclop-Eeze

Besides feeding your captive betta fish-formulated dry food, ensure to add the above types for balanced nutrition.

3. Diseases

Like other fish species, bettas are not immune to diseases. These can be infected by fungal, parasitic, and bacterial diseases that eventually contribute to curled fins.

Betta fish diseases are caused by different factors as discussed below:

  • Fungal diseases: They are mainly attributed to previous health issues, poor nutrition, exposure to toxins, and physical damage.
  • Parasitic diseases: these are caused by external parasites like ich and internal parasites like worms. They may also be caused by protozoans that live in water. Parasitic diseases may contribute to fin curling as they affect the gills of your betta fish.
  • Bacterial diseases: These result from infection from other fish, contact with foreign objects, and poor aquarium maintenance. They usually affect the fins as bacterial infections are most common in this part of betta fish.

The table below shows some betta fish diseases and their treatment:

Betta Fish DiseaseTreatment
Fin rotAdministering antibiotic medications like erythromycin and sulfadimidine
ColumnarisAdminister Oxytetracycline medication
DropsyUsing betta revive medication
FurunculosisUsing fungus clear antibiotic
Common betta fish diseases that affect fins

4. Aging

The discouraging fact about keeping betta fish is their short lifespan. Betta fish have a lifespan of between 2 and 4 years.

Age-related fin curling in betta fish is a normal occurrence and one should expect it as the fish age. As your betta fish gets older, you can notice tail loss, reduced vitality, and increased food consumption. As long as other aspects of its health are good, aging is not a cause for alarm.

Unfortunately, you can’t prevent aging in your betta fish. Some tips to help your aging betta fish include:

  • Ensuring that the water is clean and temperature regulated
  • Feeding them well with balanced nutrition
  • Avoiding physical damage to the fins by keeping aquarium objects at a distance

5. Stress

Stress in fish is a common cause of various health issues, including fin curling.

Betta fish are prone to stress for several reasons, such as poor housing, aggressive tank mates, and sudden changes in the habitat. Stress can lead to increased aggressive behavior among your bettas which may result in fin curling.

An overcrowded tank is among the leading causes of stress in betta fish. A crowded tank means the fish competes for resources like food and oxygen, exposing them to stress.

A rule of thumb is to ensure at least 5 gallons of personal swimming space for every betta fish. This way, they will not feel the pressure of competition and aggressive behavior.

You should also avoid keeping aggressive tank mates together with your betta fish.

6. Genetics

Finally, your betta fish may have curled fins due to genetics. Some genes responsible for curling fish in betta fish can be passed down from the parent fish.

Some betta fish are born with curled fins, which may be hard to notice when the fish is young. However, as the fish grows, you’ll start noticing their curled fins.

Like age-related fin curling in fish, it may be hard to reverse or treat genetic fin curling. You can, however, prevent it by choosing healthy and vibrant fish for breeding.

When you’re on the market for a new betta fish, scrutinize them and avoid selection based on color only.

7. Inappropriate Swimming

Although rare, a betta fish swimming against water currents can also end up with curled fins.

This behavior may be caused by stress, poor feeding habits, and environmental factors such as improper aquarium temperature and water quality.

You can help your betta fish achieve more balanced swimming in the tank by adjusting their environment accordingly. This includes changing the water regularly to remove excess debris, maintaining ideal temperatures, and supplementing the diet with healthy foods such as leafy greens.

Treatment for Betta Fish Fin Curling

You now know why your betta fish displays curled fins. The next step is treating this condition to restore your fish’s normalcy.

Some of the best ways to treat curling fins in betta fish include:

Maintaining Optimum Water Conditions

Water condition is the cause of many problems in most fish, including betta fish fin curling.

You need to test the aquarium regularly to ensure your betta fish is in their optimal water conditions and don’t suffer from curling fins.

The table below shows the optimal water conditions to keep your betta fish healthy and prevent issues like curled fins:

If you realize that your betta fish’s water doesn’t match the conditions on the table, you can take the following actions:

Water ConditionOptimum Level
Temperature24.4 to 27.7°C
AmmoniaBelow 0.5 ppm
NitriteBelow 0.5 ppm
pH6.5 to 8
OxygenNot less than 5 ppm
Optimum water conditions for betta fish
  • Conduct a water change: Regular water changes are essential because they remove debris and harmful toxins from the water. It’s advisable to perform weekly water changes for your aquarium. Smaller water tanks of less than 150 gallons requires a 10 percent water change weekly. If you have a bigger water tank whose capacity exceeds 150 gallons, a 20 percent water change will work well.
  • Use reverse osmosis: If you realize that the water’s pH is not optimum, reverse osmosis is the best remedy. Alternatively, you can deionize the water using a deionized.
  • Add aquarium salt: Adding aquarium salt can help stabilize the water and reduce the onset of curling fins in your betta fish.

Expert Tip: When conducting a water change, remember to avoid tap water since it’s chlorinated and can cause more harm than good for your fish.

It’s also important to note that certain medications used in treating diseases can alter the water’s pH. For example, organic acids increase the acidity of water, while basic compounds such as sodium bicarbonate have the opposite effect.

Prevent Overcrowding

Tank size is essential if you want to prevent stress in your betta fish. This is especially true with conditions like fin curling that can be triggered by overcrowding.

We recommend that you ensure the aquarium’s water tank has enough space for your betta fish to swim, feed, and generally move around comfortably.

The minimum recommended capacity of a betta fish aquarium is 5 gallons per fish. Bettas also require a mean population density of 1.7 animal per square meter. Therefore, if you’re looking to breed your betta fish, provide more space if you want healthy and vibrant fry.

Quarantine a Sick Betta Fish

A sick betta with bacterial or fungal disease needs quarantining to manage the condition and prevent it from spreading to other fish. This can help prevent curling fins in other betta fish in the same tank.

You’ll need a hospital tank to quarantine your sick betta fish correctly. A hospital tank should meet the following conditions:

  • Be at least 10 gallons
  • It must have an established biological filter
  • It has a chemical filter
  • Has a heater and air pump for sufficient water circulation

You should remember to keep the quarantine system as clean as possible by conducting regular water changes.

Frequently Asked Questions

How Do You Treat a Betta Fin Curl?

You can treat a betta fin curl by maintaining water temperatures between 76 and 85 degrees Fahrenheit (24.44 and 29.44 degrees Celsius) and a pH between 6.8 and 7.5. The best way to achieve these requirements is by conducting a 20% water change regularly.

How Do You Know If Your Betta Fish Has Fin Rot?

You can know if your betta fish has fin rot by observing its coloration. Fin rot in betta fish is identified by whitish, reddish, and sometimes blackish fins. The fins will also appear ragged and shorter than normal. In severe cases, rotting betta fins will have some parts breaking and falling off.

What Causes Clamped Fins in Betta Fish?

Poor aquarium water parameters are the main cause of clamped fins in betta fish. These parameters include temperature, pH, and the presence of ammonia, nitrites, and nitrates. Therefore, you should conduct a 20% water change regularly to maintain the optimal betta fish water parameters and prevent clamped fins.

Final Thoughts

Betta fish fin curling is a situation you must deal with urgently for the fish’s safety. In most cases, the situation arises from poor aquarium conditions.

Given the right aquarium conditions, you can help your betta fish achieve a healthy life with little or no fin curling.

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