Do Fish Turn Black When They Are Sad?

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One of the main attractions of fish is their vibrant color. Little wonder why it is not surprising when owners get concerned with black patches on their pets. Owners worry that something might be wrong and this could be the case.

Even though there are several reasons why your fish could turn black, one major reason could be that your fish is sad. So, your fish could be turning black because it is sad.

In this article, we will therefore be exploring why your fish could get sad and ultimately make them have black patches. We will also consider some other reasons why your fish could turn black.

So, let’s get started.

Do Fish Turn Black When They Are Sad?

Julian Pitman, a professor at Troy University in Alabama stated that fish can also suffer from depression and you can diagnose the symptom as well. This could also be a reason why your fish suddenly starts turning black.

Fishes like any other pets react to human emotions and health conditions. This means that a dip in your fish’s health could affect it too. Fishes that are usually depressed or sad will not have the interest to explore or eat or in some cases, both.

What Makes a Fish Get Sad?

If you have ever noticed your fish at the bottom of the tank looking glum and black, it means that depression could be lurking around your fish. According to researchers, fish can get sad and depressed too. The level of depression your fish is experiencing could be based on how long it hangs at the bottom of the tank.

Fishes generally love to explore their environment and swim-up top. So, if this is not happening, it means that your fish could be sad. Small tanks with poor water quality and low oxygen can be a reason why your fish gets sad. So, to prevent your fish from looking all glum and sad, you have to ensure that the tank is in the right condition.

Adding plants to nibble on and cages to swim through in their tanks could help your fish stop feeling sad and make them come alive again. This will make their environment more aesthetically pleasing and provide them with plenty of entertainment. This will lead to a reduction in stress and it will promote brain growth.

What Are The Other Reasons That Can Make Your Fish Turn Black?

Apart from your fish being sad, there could be some other health issues responsible for your fish turning black. Although there are still some relatively innocent causes. So, let’s explore a few of those reasons.

I. Ammonia in the Tank

Ammonia changes are one very common reason why your fish could be turning black. This colour change usually starts from the fin of the fish and then will moves to other parts of the body. Then, it will appear like small batches of black skin that are burnt.

Ammonia is a toxic chemical that is produced in your fish’s aquarium. Most people don’t know but caring for the fish in captivity is a race of preventing ammonia buildup in the tank. This is the reason why a filtration and cycling system is very important.

Fishes can produce ammonia through waste. Decaying plant matter and food particles could also be responsible for the production of ammonia. You can keep the ammonia levels low by simply keeping the tank clean periodically. A good filtration system can help as well.

Water changes are the best way for you to get rid of this chemical fast. When you do not change the water regularly, ammonia levels can build up too fast. This chemical has the potential to kill your fish apart from making it turn black.

Sick and stressed fish can also release a lot of ammonia and high levels of this chemical only worsen the situation. So, check the water conditions and remove any dead plants or leftover food. You might also want to consider changing the way you feed your fish too.

II. Genetics

Some specimens of goldfish are genetically predisposed to colour changes. Even though a goldfish turning black is rare, it is still very possible. Goldfishes that are mixed breed are likely to go through changes across their lifespan.

These fishes could sometimes change colors when they transition from the juvenile stage to the adult stage. This might occur in the first or second year. The change is usually progressive so you might not notice it at first. These goldfish may develop darker patches in the body while some areas start becoming lighter.

It is also possible for a purebred goldfish to turn black as well. In these fishes, the change is usually more subtle and you might see black spots develop on the fins. Whatever the case may be, fish turning black could be because of a genetic trait and might not necessarily be a health condition.

III. Disease

Fishes turning black due to a disease is rare although it is still a possibility. This disease is called the black spot disease. This disease is common in fishes that are kept in ponds rather than in aquariums. It could also affect fishes in the wild.

This blackspot disease is a parasitic fluke disease that fishes get infected with through water snails. Fishes in ponds can also be victims of this disease if bird droppings make their way into their ponds. When fishes have this disease, they will develop black spots over all their bodies.

The infestation of this disease can vary quite as well. In some instances, you could see mild spots here and there. Serious infestations could however cover the entire goldfish in black.

If you suspect that a disease could be the issue, observe your fish’s behaviour. These spots are usually itchy so fishes will most likely flick their bodies and want to rub them against surfaces to get relief. Although this disease is rare, it is still a possibility.

To treat this disease, you have to eradicate water snails from the environment. This can break the parasite’s life cycle. It might take a while but your fish will recover. This disease is less dangerous than ich.

Can Your Fish Return To Its Original Colour?

Fishes turning black may or may not retain their natural color. It ultimately depends on the cause of the change and prognosis. If the cause of the colour change is because your fish is sad, then it can go back to its natural colour. Changing the mood of your fish by giving it a vibrant environment will help it go back to its natural colour.

If the black colour is a genetic trait, however, your fish may remain that way for the rest of its life. Even though you might not have planned for the colour change, it is not something that will affect your fish’s health in any way.

If the colour change is due to ammonia poisoning, then eradicating ammonia would be the best way to go. Your fish will return to its natural colour gradually. Although this might not be an instant change.


Seeing your fish darken can cause some serious concerns at first, however, it might just be something you need to correct.

Your fish might be sad and all it needs is to switch up its environment. So, you have to be very observant with your fish.

Written by Justin Michaels

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