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3 Tips to Prevent Black Spots On Betta Fish

black spots on betta fish

Betta fish comes in various colors, and some species of betta fish even change their color over time. While this is a common trend in betta fish, you may sometimes notice some black spots on betta fish. It would help if you did not ignore such development of black spots on your betta fish.

There might be several causes for such black spots on betta fish. Among the most common ones are the black spot disease and velvet. Both these diseases are treatable if spotted as soon as possible. Symptoms of these diseases are pretty obvious. It causes your betta to develop several black spots all over its body.

Causes Behind Black Spots On Betta Fish

As stated earlier, there can be several reasons behind the development of black spots on betta fish. In some cases, this happens naturally as the betta fish ages. On the other hand, in some cases, the spot’s development may be due to certain illnesses that may affect your betta fish.

The two most common causes behind developing black spots in a betta fish are the velvet parasite and the black spot disease or the tang disease. Both these diseases are easily treatable if their symptoms are noticed as soon as possible.

Let us discuss in detail the causes, symptoms, and treatment for each of these diseases.

black spots on betta fish

1. Black Spot Disease

The parasite that causes black spot disease is most often seen in tangs and other surgeonfishes, but it can also infect other fish species and mollusks like shellfish. Black spot disease is sometimes known as the tang disease or black ich, despite the fact that a different parasite causes ich.

In the black spot disease, small paravortex turbellaria flatworms are lodged in the fish’s skin. This is what causes the black spots on betta fish. Black spot parasites are far less severe and fatal than other parasites. Thus, if identified early, they are a lot easier to treat.


When these worms (paravortex turbellaria) feed on a host fish, they develop melanin pigmentation, which appears as black spots on the body and fin membranes of the betta fish, approximately the size of a grain of salt.

Because the spots do not always remain fixed, the worms may freely move about on the fish’s body. They are easily visible on light-colored fish, but they may be hard to spot on dark-colored fish. Infested fish scrape against objects or the substrate in an attempt to expel the parasites.

If the infection is allowed to spread, the betta fish will become lethargic and lose their appetite and colors, and if the gills are damaged, shortness of breath may occur. Secondary bacterial infections may also appear on such open wounds caused by the worms.


To treat the diseased fish, give all infected fish a freshwater dip, then a formalin bath, and keep them in a quarantine tank for the rest of the therapy. In quarantine tanks, praziquantel can be used to treat infected fish.

If these parasitic turbellarian worms are not eliminated from the main tank, reinfection will occur regardless of how well the fish have been treated. Unfortunately, because they may survive without a host for several months, this is not always simple.

Young worms dwell on the substrate and eat organic waste until they are ready to find a fish host. Controlling their numbers can be as simple as sucking out the extra organic debris that accumulates at the bottom of the tank.

If you believe your betta fish is ill, contact your veterinarian right away. Always consult your veterinarian for health-related issues since they have evaluated your fish, are familiar with your fish’s medical history, and can offer the best suggestions for treatment.

2. Forgot to Change Water

If your betta fish are showing symptoms of black spot around the body. There are high chances that the environment in which betta fish is living is not adequate for them. Stale water and unfriendly environment can lead to the problem of black spots. Betta may get tensed when the surroundings are not jovial.


What you can do in this situation is change 25-30% of water daily, use aquarium salt if required. Bettas require a minimum of 3 Gallon tank to inhabit properly. And also make sure you are not overcrowding the tank with many species.

Use sponge filter and if the temperature is not suitable for bettas you may us the water heater. Do these changes for a week and keep inspecting if the spots are dropping.

3. Velvet

Velvet is a parasite afflicted betta fish that results in a rust-like color over the betta’s body, gills, and fins. It is difficult to diagnose a betta fish suffering from velvet and is best detected by shining a light source, such as a flashlight, on the betta.


Velvet-infected betta fish have rusty skin and a scaly head, including the gills and belly, as well as black spots on betta fish or markings all over the skin, causing color loss. Make sure you rule out the possibility of marbling and distinctive coloration in betta fish first.

Betta fish have also been observed to change color over time. Bettas with velvet will rush about the tank, searching for areas to rub themselves on in an attempt to get rid of the parasites just like ich. Velvet can be fatal if left untreated.


This parasitic illness may be avoided by increasing water quality and maintaining stress-free living conditions in the tank. Water conditioners are among the most effective chemicals for enhancing living circumstances. Even though velvet is exceptionally infectious, the API Bettafix can treat it.

This medicine, made by Aquarium Pharmaceuticals, contains curing ingredients including sodium chloride, copper sulfate, acriflavine, formalin, sulfa 4 TMP, methylene blue, and malachite green. It is also readily available over Amazon.

Velvet is very infectious among communal fish, particularly among sororities. Even if the other fish in the tank appear healthy and show no indications of sickness, treat the community tank. Continuous stresses, poor water conditions, and extended exposure to cooler water temperatures can cause velvet in bettas.

Recommended Reading | Reasons Why Betta Fish Staying in corner of the Tank

FAQs Related to Black Spots On Betta Fish

How do you treat velvet in bettas?

Raise the temperature of the water and dim the lights. Add aquarium salt and copper sulfate to the tank water. You can also use the API Bettafix that contains all the necessary curing ingredients to treat your infected betta fish.

Why is my betta turning gold?

If your betta is suffering from velvet, then the gold coating may be caused by your fish generating too much mucus in an attempt to combat the illness. Thus, the development of gold coat in the betta fish is a natural prevention measure adopted.

Why does my betta have black spots?

Some betta species develop black spots over time with age. In contrast, some develop these spots due to some illness. The two most common diseases that cause such black spots are velvet and the black spot disease.

Can black spots kill betta fish?

Yes. Black spots can kill a betta fish if you ignore them for a long time. Thus, it is recommended to look out for various bacterial infections if you see black spots on betta fish.

Final Thought

While in some cases, it is part of the natural aging process, the development of black spots on betta fish may also be due to certain kinds of illnesses like velvet or the black spot disease. These diseases are easily treatable if identified as soon as possible.