do goldfish need a filter

Why Do Goldfish Turn Black ? | 5 Triggers

Find Out Why Do Goldfish Turn Black ? | 5 Triggers identified


Goldfish is one of the most popular pets for an aquarium as they look the most attractive while inside an aquarium. There are a lot of other benefits of including goldfish in your fish tank. But if you are to include goldfish, you should learn to take optimum care of them so that they remain happy and healthy. Nowadays more and more people are keeping an aquarium in their home, Aquariums are great for improving the aesthetics of the house, relaxation, and are also a great conversation starter when you have visitors. Having goldfish in your tank makes it very attractive.

Obviously, any time a fish turns black, this can be an that your Goldfish is not in good health and you immediate attention is required to investigate what might be the cause.

Benefits of Having Goldfish As Pets

The following are the benefits of having goldfish in your fish tank:

  1. They are among those fish species which are easily available for people to keep as pets. Some other species of fish may not be readily available locally in the aquarium stores.
  2. The also fall under the class of fish considered as low maintenance.
  3. The also aren’t expensive and do not have a specialized diet and their ideal food is available in most supermarkets and aquarium stores.
  4. Keeping goldfish in your fish tank is also a hobby which you can easily commercialize by breeding them and then offering them for sale.

Why do Goldfish Turn Black ? 

Goldfish are the most colorful species among all the aquarium fishes. Including them in your fish tank gives a beautiful contrast of colors which is great to look at. In a due course of time, the nature of the goldfish can change or vary because of the aquarium conditions. Following are the most common reasons why goldfish turn black:

These are 5 triggers which are fairly common in triggering their change in color.

1) Ammonia Burns up

This is actually the most frequent reasons that they change color. Ammonia is produced inside the fish tank due to excess fish food in the tank which eventually decomposes and if the water in the tank is not being adequately filtered/Cycled. The ammonia itself  does not cause the skin to turn black, but the healing process which happens naturally turns their color to black.

In the event the water isn’t correctly filtered and cleaned out frequently, that toxins may cause burns up to the goldfish. That black color is actually a sign the infection is healing, and so cleaning out the container correctly can help make sure the infection does not come back. With time, that goldfish should certainly go back to normal color.

2) Change of color caused by environmental factors

The location of your aquarium can also affect the color of the skin of your goldfish. It is advisable that an aquarium should be kept in a well lit area. This is because when the fish are kept in a dark area they tend to secret  a black pigment known as melanin which may appear as black patches on the skin of the fish

3) Temperature of the water

It is important to select the location for your tank away from sources of  heat such as direct sunlight and high and bulbs and lamps that may emit hig amounts of heat when in operation. Small tanks will also tend to heat up more quickly when exposed to hot environments.


4) That tank is actually small

The fish tank might too small which may lead to faster saturation  of ammonia and carbon in the tank due the low water volume present. It is common to start out with small tanks as most of the fish bought from the Pert stores are usually small in size. The downside is that as the fish grow in size we tend to overlook the need to move them to an appropriately larger size tank.


Buying a 10 or 20 gallon container for your fish is usually adequate to ensure the goldfish has lots of space to thrive in the water.  Keep in ind the ideal tan size will be dependent on the quantity and size of fish you put in the tank. for larger sizes and quantities you could even scale scale up to 40 Gallon breeder tank.

This rapid build up of toxins in the small tank present greatly increases the chances of your fish contracting disease.

5) Disease May cause Goldfish to Turn Black.

Including water snails along with the goldfish in the same tank is a a bad idea as the snails considerably increase the chances of your fish contracting disease from the snails.

There is disease  known as schistosomiasis which is a parasite carried by freshwater snails and is spread by water contamination. That eggs of the parasite casing this disease, burrow deep into the pores and skin of the Goldfish and form protective very hard cysts that are black in color. The consequence of this infestation causes the overall look of black spots in the Goldfish.


Optimum Care and some precautions to avoid Problems

After finding out why do goldfish turn black, you need to find the optimum solution.  But you don’t need to panic every time your goldfish develop some dark patches on their skin as the the patches to often tend to clear up quickly sometimes there is not much going on with the fish.


It is also important that sometimes goldfish will naturally turn change color for short duarations due to reasons that are purely natural for them.

If you can’t quite pinpoint the exact cause of the change in color, it is advisable to consult with your veterinarian for professional advice.