Why is my betta fish turning black?

In this post, we will answer the question “Why is my betta fish turning black?”. We will also discuss de possible causes and what you should do in case your betta fish turns black.

Why is my betta fish turning black?

Betta fish are known to turn black as they grow in size. It shows up most prominently in their fins, which gradually get darker as they increase in length. Bettas, on the other hand, can become black as a result of environmental causes. Inappropriate water conditions, stress, and infections, such as black spot disease, are examples of such factors.

Genetic factors (Marble gene)

Bettas with the marble gene have a modest alteration in skin pigmentation that does not influence their overall health. In general, the fins and tail of a fish carrying this gene have a dark bluish hue to them. This gene may be responsible for a fish’s black shading on its ends. 

Because of this gene, the pigment that makes up the betta’s skin begins to alter in appearance. Depending on whether or not the betta possesses this gene, it may begin to turn almost black forever. Because it is a dominant gene, it will manifest itself in the progeny of the fish that is afflicted. The fish with this gene may have a modest amount of colour in the fins and tail, even though it is quite unusual. 

Bettas with the marble gene will normally darken by the time they reach the age of two. So if your betta is becoming black and it’s less than a year old, it’s unlikely that it’s due to this particular gene. With time, the fish will turn darker and darker in colour.

Inappropriate water conditions

The water quality of your betta’s tank has a huge impact on how healthy it will be. One issue is that a large number of bettas are placed in a dirty tanks with inadequate water conditions. So the first thing you should do after purchasing a new fish is to do a water quality test. 

For example, ammonia poisoning can cause the scales of your betta to become black as it does in goldfish. Ammonia levels often rise in congested tanks because it is produced as a byproduct of uneaten fish food and excreted urine. The same may be said for nitrates and nitrites as well. 

I would also recommend considering the pH. When the pH of the water is too high, or when the water is too acidic, it might harm the health of your betta. Bettas thrive in water with a pH between 6.8 and 7.5, while they may tolerate slightly lower pH levels. 

The temperature of the water is another important consideration. Bettas thrive at temperatures ranging from 75 to 80 degrees Fahrenheit. Water variations regularly, as well as water that is too cold or too hot, might stress your bettas. This, in turn, might result in the use of dark shades.

Black spot disease

This illness, also known as diplopstomiasis (betta fluke disease) or black spot disease, is one of the most frequent parasitic diseases that plague bettas. It is a parasite that may be transmitted by the use of contaminated water or overcrowding in tanks. Bettas get black patches as a result of the parasite consuming their skin. 

Bettas are parasites that spend the initial portion of their lives in the water before attaching themselves to their fins or bodies. It may also spread from tank to tank by the use of water and nets, among other methods. It commonly manifests itself as little black specks or spots on the body of the bettas. 

Bettas suffering from this ailment may seem very sluggish, thin, and may even lose their colour due to the condition. Additionally, they will lack balance and will swim in unpredictable patterns. The accumulations of black dots at certain spots on the fish’s body, on the other hand, are the most visible indicator of the disease.


Stress may harm the health and colour of your betta. It might express itself as black fins or scales in rare circumstances. Bettas housed in overcrowded tanks or with aggressive tank mates, for example, may display indications of stress and anxiety. 

The most prevalent problem involves having an excessive number of bettas in a single tank. As a general rule of thumb, one betta should be kept for every twenty gallons of water in the aquarium. If you keep your betta in a tank that is too tiny, it will be forced to engage in pointless interactions and aggressive behaviour. 

This is especially true for betta fish that are male. They have a natural need to defend their area and will engage in combat with other male bettas. It may also occur if the bettas are maintained with aggressive tankmates, such as very aggressive cichlids.

The tank is not cycled

Bettas are best compatible with a tank that has been cycled. Cycling is the process of producing biological filtration in an aquarium, and fish must survive in such an environment. Furthermore, because bettas are extremely susceptible to ammonia poisoning, keeping their tank cycled will assist to keep their health in control. 

Cycling properly takes between 6 and 8 weeks on average. Inoculating the aquarium with helpful bacteria through the use of a bacterial inoculation product can help to accelerate tank cycling. You should avoid utilising any additives that include ammonia, on the other hand.

Do bettas get darker as they age?

Especially if they are kept in less-than-ideal circumstances, bettas get darker as they grow older. Bettas that are in good health, on the other hand, may become darker as a result of the marble gene. This will be most noticeable in the distal portions of their ends and is unlikely to result in a darkening of their scales. 

In their later years, when they approach the age of five, bettas often lose their colour and become paler in appearance. The reason behind this is that their capacity to generate melanin is diminishing. Of course, this occurs as they grow older, but it may also occur under particular stress situations.

What should I do if my betta is turning black?

If you have a betta that is becoming black, the first thing you should do is rule out environmental variables. It then comes down to genetics and natural development, assuming that everything checks out well.


In this post, we answered the question “Why is my betta fish turning black?”. We also discussed de possible causes and what you should do in case your betta fish turns black.

If you have any thoughts or doubts, feel free to drop us a comment below!

Frequently Asked Questions (FAQs): Why is my betta fish turning black?

How can I tell if my betta fish is dying? 

Other symptoms that a betta fish is ready to die to include discolouration along the fish’s body, such as white or brown blotches, and the presence of parasites. Swimmers with severe swimming ailments may exhibit unusual motions or shortening / eating away from the ends of their strokes. 

What can I do to restore the colour to my betta fish? 

Constipation and light colouration may occur in your Betta if he is fed a diet that is mostly composed of fish food. He will return to his vibrant colour if you feed him a mashed, cooked pea to help things along. 

Is it possible to bring a betta fish back to life? 

However, if properly cared for, your Betta Fish may live for up to six years in a happy environment. If you believe your Betta Fish is near death, there are several options for treating its health and reviving it. While the majority of illnesses are treatable, a handful is potentially deadly. Betta fish are also referred to as Siamese fighting fish, which is a more formal term. 

What caused my betta to become black? 

Stress, old age, accidents, and disease are all possible causes of colour loss in your betta. It is also possible for Bettas to lose colour on their own, especially if they carry the marble gene. As long as there are no other indicators of sickness in your betta, you shouldn’t be too concerned about their colouration changing. 

What happens when the colour of a betta fish changes? 

If your Betta’s colour is steadily shifting but otherwise looks to be in good condition, it is most likely carrying the Jumping Marble gene. Transposons and Marble genes are two terms used to describe these sorts of genes. Betta fish that have them are distinguished by the splotches of random body colouring that appear on their bodies. 

Is it usual for bettas to alter their colour while they mature? 

Betta fish respond to stress by changing the colour of their skin. The loss or dullness of a hue is the most common manifestation of the transformation. When the tension becomes too great for them, they may momentarily lose their colour. Betta fish can also acquire a condition known as “stress stripes” in other circumstances.


Why is my Betta Fish Turning Black? https://petfishonline.com/betta-turning-black/

Betta Fish Turning Black. https://www.myaquariumclub.com/betta-fish-turning-black-1139309.html

Song, M. (2006). Caring for Betta Fish. Lulu. with.