Black-Stripe in Discus (Black-Stripe Syndrome)

This is a ciliated protozoan that attacks fish including discus fish. It is called Cryptobia. This is an internal disease of the fish where the Cryptobia organism is creating granulomas in the fish.

Symptoms of Black Stripe

Most times the coloration is always black and it is seen on the head alongside one or two vertical stripes on the body as well. And some other times only the head or the tail turns black.

NOTE: Sometimes only one side of the head is affected.

Causes Of Black Stripe

The cause of this black stripe in fishes is not clear, but some references on the internet affirm that the stripe does not have pin pointed cause.

NOTE: There are some other reasons why a Discs fish might have black stripes rather than the Cryptobia protozoan, such as the Discus being stressed, and that’s why the black stripes called the stress bars.
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Discus Black Stripe Treatment

There is no medication or treatment for it. It often just goes away on its own and doesn’t seem to be very contagious.


Research shows that this protozoan cause black pigmented areas to appear on Discus fish, and these are most times in large stripe, while some other parts of the body and fins usually will take on a lighter and faded out coloration. These stripes are called the black-stripe syndrome.


This is me Firas Sameer, the founder of, I am an aquarist guy with a passion and love for Discus fishes, I am learning every day with my hobby at home and sharing the things I am learning from my experience with you.

One thought on “Black-Stripe in Discus (Black-Stripe Syndrome)

  1. One of my discus have a black strip on their eye but then it fades away same as his color but comes back as well. Should I do something about it or will he be okay?

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