Betta Fin Rot 101: Causes, Symptoms, Treatment, and Prevention

betta fin rot

Betta fin rot, aka tail rot or melt, is an incredibly prevalent disease among aquarium fish. It eats away the delicate and beautiful finnage bettas are known for.

It is typically caused by gram-negative bacterial or fungal pathogens that occur naturally in tank water. However, it is only under particular conditions that they compromise the health of the fish.

If a betta fish has a weakened immune system, it is more susceptible to being infected by those pathogens. When we notice that our fish may be developing fin rot, we need to act quickly to prevent the disease from spreading further as, if left untreated, it can endanger the life of our pet.

What Causes Betta Fin Rot?

Poor water conditions are a breeding ground for bacteria. If the fish have weakened immune systems, they are prone to a fin rot outbreak. There are many factors that can compromise the immunity of our fish:

  1. A small bowl
  2. Poor nutrition
  3. Overcrowded aquarium
  4. Uncycled water
  5. Unheated tank
  6. High ammonia, nitrite, and nitrate levels

Small bowls are high stressors for betta fish as they need enough space to swim around. What’s more, tiny tanks have less water that can become dirty sooner than the water in larger ones and can lead to various infections in the fish.

The same goes for aquariums with many fish. The more fish we keep in a single tank, the more bioload they leave in it, and the dirtier it gets.

Inconsistent feeding can jeopardize the well-being of betta fish. It weakens their immune system and contributes to the development of many diseases, including fin rot.

Also, it’s good to keep in mind that bettas are tropical fish. If we keep the tank water too cold for them, we risk their health.

Another factor that causes stress to betta fish is high ammonia, nitrite, and nitrate levels. They can compromise their immune systems and make them susceptible to developing fin rot.

It should be noted that, sometimes, the fins become damaged from fighting, snagging sharp decor, or biting. If that is the case, we will know that the fish isn’t suffering from fin rot as there won’t be any fin discoloration.

What Are the Symptoms of Betta Fin Rot?

Depending on how long the fish has been infected, it will manifest different degrees of fin rot. Generally, the disease can be broken down into three stages: mild, moderate, and severe.

Mild Fin Rot Symptoms

In the initial stages, betta fin rot manifests itself through slight discoloration of the fin’s edges. They become slightly darker and look jagged. In the case of a fungal infection, we can observe whitish tips or spots. Generally, the rot is located only at the ends of the fins.

Moderate Fin Rot Symptoms

As the disease progresses, the fins appear more receded and start turning noticeably black with obvious dead tissue patches. Apart from the significant reduction of fins, we can see white patches, fuzzy growth, and red spots on the edges.

Severe Fin Rot Symptoms

At this stage, we can observe a serious deterioration or even the loss of the entire fin. There are inflammation and redness at the base of the fin, and the infection can spread to the body of the fish. In that case, we can see blood and rotting flesh on the body of the fish. The behavior of the fish is altered as well — it has difficulty swimming, is lethargic, and has lost appetite. If the condition this progressed is left untreated, the fish may die.

What Is the Treatment for Betta Fin Rot?

The sooner we catch the disease, the better. The treatment depends on the severity of the symptoms. In case we have more than one fish in the same aquarium, we should put the one infected in quarantine until it recovers.

In the initial stages of the infection, we recommend changing the water and adding aquarium salt to it, as it has antibacterial properties. There is no need to medicate the fish, as with the improvement of its living conditions, the symptoms should start to subside. We can expect the fish to make a full recovery on its own as soon as its immune system grows stronger.

In the more advanced stages of the disease, all of the above applies, but we may also need to introduce some antibacterial or antifungal medication. We would recommend API Pimafix for a fungal infection and API Furan 2 for the bacterial one.

How Do I Know That the Condition Is Improving?

If the treatment is going according to plan, our fish will show instant signs of recovery. Here are some to look out for:

  • The discoloration is disappearing — there are fewer dark spots, red spots are receding, and white edges are gone
  • The fish is more lively
  • There is a clear membrane on the fins’ edges — that is a sign of regrowth, although in many cases, the fins do not regrow
  • Edges appear less jagged and torn
  • Fuzzy growth has disappeared from the finnage

Is There Anything I Can Do to Prevent Betta Fin Rot?

The best course of action to prevent fin rot is to make sure the fish is exposed to as little stress as possible. That means choosing the appropriate tank size, cleaning it and changing the water regularly, maintaining the right water temperature, and feeding the fish properly.

Tank Size

Betta fish should have enough room to swim about, so pick a tank that allows for sufficient space for your fish, especially if you have more than one. Bettas are highly aggressive by nature, so allowing them their own space will reduce the number of attacks.

On top of that, a larger aquarium requires less frequent water changes as it takes more time to become cloudy, especially if you have a filter.

Cycled Aquarium

Fish excrement fills the water with ammonia, which is toxic for fish. However, frequent water changes also stress the fish. The best method to ensure we don’t disturb them unnecessarily is to filter the water.

That way, we won’t have to change it as much, and even when we do, partial water changes are enough. We should strive to keep nitrate at 20 ppm (parts per million) and ammonia and nitrite at 0 ppm for optimal water quality.

Water Temperature

As we mentioned, bettas are tropical fish. The water temperature in the tank should mimic the one in their natural environment. Although bettas can survive in unheated tanks, they won’t have a happy life and won’t be able to thrive. We recommend keeping the water temperature somewhere in the neighborhood of 78°F.

Proper Diet

Bettas feed on insects, so if you can, feed them with live worms every once in a while. We recommend Grindal worms, vinegar eels, and brine shrimp. Alternatively, go for a mix of freeze-dried foods and dry pellets. Avoid overfeeding or underfeeding them, as it may also weaken their immune system.

Bonus Tip

Betta’s fins are extremely delicate, especially when ridden with this disease. We should remove any sharp objects from the tank until the fish heals. It is also wise to isolate the sick fish from others to curb the risk of fighting and damaging the fins even further.

Final Thoughts

All in all, betta fin rot is a common but entirely preventable disease. Making sure our bettas have optimal living conditions should keep fin infections at bay. If the disease does appear, we should try to catch it in its beginning stages. Changes to the color and shape of the fins are tell-tale signs that there is a problem. Remember that a beautiful fish is a happy fish!