How to Care for a Black Ghost Knifefish

Co-authored by Craig Morton

Last Updated: August 3, 2024

From the Amazon river comes a beautiful species of nocturnal fish. Growing up to 20 inches (49 cm), the black ghost knifefish has a spot in the heart of every fish keeper.

Part 1

Part 1 of 2:

Providing a Good Habitat

Download Article

{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/3\/31\/Care-for-a-Black-Ghost-Knifefish-Step-1.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-1.jpg","bigUrl":"\/images\/thumb\/3\/31\/Care-for-a-Black-Ghost-Knifefish-Step-1.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

1
Get a large enough tank. In the aquarium world, the knifefish is a large fish that needs a large tank. It is suggested to use a minimum of a 125-gallon tank for a single knifefish. You should do 30-50% water changes each week.
- The knifefish will spend most of its time in the bottom of the tank.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/4\/43\/Care-for-a-Black-Ghost-Knifefish-Step-2.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-2.jpg","bigUrl":"\/images\/thumb\/4\/43\/Care-for-a-Black-Ghost-Knifefish-Step-2.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

2
Keep that water warm. The temperature your tank should be between 73 and 83 degrees Fahrenheit (22.8-27.8 degrees Celsius). You will need a tank thermometer to tell the water temperature inside the tank. A tank heater may be needed (depending on where you live) to get the water to an acceptable temperature range.
- If the water temperature is under 73 degrees Fahrenheit (22.8 Celsius), The fish could become sluggish or to lose its appetite.
Advertisement
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/b\/bf\/Care-for-a-Black-Ghost-Knifefish-Step-3.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-3.jpg","bigUrl":"\/images\/thumb\/b\/bf\/Care-for-a-Black-Ghost-Knifefish-Step-3.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-3.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

To find the pH of the tank you will need pH strips.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/5\/53\/Care-for-a-Black-Ghost-Knifefish-Step-4.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-4.jpg","bigUrl":"\/images\/thumb\/5\/53\/Care-for-a-Black-Ghost-Knifefish-Step-4.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-4.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

The substrate should be either sand or gravel to replicate the knifefish's natural environment. The substrate needs to be fairly soft to prevent harm to your fish.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/0\/09\/Care-for-a-Black-Ghost-Knifefish-Step-5.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-5.jpg","bigUrl":"\/images\/thumb\/0\/09\/Care-for-a-Black-Ghost-Knifefish-Step-5.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-5.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

5
Provide many hiding places for your fish. Whether your decorations are plants, rocks, or wood, you should have many decorations to help your knifefish feel secure.
- Some owners have a clear tube in the tank so the owner can see the fish but the fish still feels secure.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e1\/Care-for-a-Black-Ghost-Knifefish-Step-6.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-6.jpg","bigUrl":"\/images\/thumb\/e\/e1\/Care-for-a-Black-Ghost-Knifefish-Step-6.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-6.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Choose a tank mate that is about the same size as your knifefish. These fish are peaceful to other fish that are the same size as them but, can become aggressive with other ghost knifefish. Make sure your tank mate isn't too small so it isn't mistaken for a meal.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/d\/d4\/Care-for-a-Black-Ghost-Knifefish-Step-7.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-7.jpg","bigUrl":"\/images\/thumb\/d\/d4\/Care-for-a-Black-Ghost-Knifefish-Step-7.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-7.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Coming from the Amazon river, knifefish are used to moderate to strong water flows. A good water flow gives your fish mush needed exercise to keep it healthy.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/77\/Care-for-a-Black-Ghost-Knifefish-Step-8.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-8.jpg","bigUrl":"\/images\/thumb\/7\/77\/Care-for-a-Black-Ghost-Knifefish-Step-8.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-8.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Knifefish are nocturnal and used to hunting in the dark. During the day, use none or very little light. At night, use some low-level lighting so you can see the fish when its active.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/6e\/Care-for-a-Black-Ghost-Knifefish-Step-9.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-9.jpg","bigUrl":"\/images\/thumb\/6\/6e\/Care-for-a-Black-Ghost-Knifefish-Step-9.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-9.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Make sure your filter can any and all waste and impurities. Knifefish are very sensitive to things in the water like ammonia, nitrites, and nitrates.

Part 2

Part 2 of 2:

Feeding

Download Article

{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/69\/Care-for-a-Black-Ghost-Knifefish-Step-10.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-10.jpg","bigUrl":"\/images\/thumb\/6\/69\/Care-for-a-Black-Ghost-Knifefish-Step-10.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-10.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

1
Feed live food. In the wild, the knifefish eats insect larva, insects, worms and small fish so replicate this diet in your tank. To replicate the diet you can use foods such as:
- Brine shrimp
- Bloodworms
- Blackworms
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/1\/1d\/Care-for-a-Black-Ghost-Knifefish-Step-11.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-11.jpg","bigUrl":"\/images\/thumb\/1\/1d\/Care-for-a-Black-Ghost-Knifefish-Step-11.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-11.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Once acclimated, your knifefish should come out for feeding. If you see that your fish is shy, feed it multiple times a day to help it get used to coming out. These fish are one of the few fish that you can hand feed. Hand-feeding requires a good bond between the fish and the owner so don't expect to be able to right away. When hand feeding, make sure that you don't have any soaps or perfumes on your hand because these are toxic to fish.
{"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/1\/1d\/Care-for-a-Black-Ghost-Knifefish-Step-12.jpg\/v4-460px-Care-for-a-Black-Ghost-Knifefish-Step-12.jpg","bigUrl":"\/images\/thumb\/1\/1d\/Care-for-a-Black-Ghost-Knifefish-Step-12.jpg\/aid9800271-v4-728px-Care-for-a-Black-Ghost-Knifefish-Step-12.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"<div class=\"mw-parser-output\">\u00a9 2024 wikiHow, Inc. All rights reserved. wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. This image may not be used by other entities without the express written consent of wikiHow, Inc. \n<\/p> \n<\/p><\/div>"}

Sickness can be transferred from anything from plants to feeder food. Make sure to properly quarantine anything that you add to your tank and to only buy your food from reputable sources that you trust. Knifefish are prone to skin flukes, parasitic infestations (protozoa, ichthyobodo, worms), bacterial infections, and bacterial diseases.

Community Q&A

Search

Add New Question

Question

Can I feed artemia to black ghost knife?

Community Answer

Yes. Feeding brine shrimp to a black ghost knife fish is perfectly okay. You can also try sinking carnivore pellets. You can feed blood worms, tubifex, brine shrimp, or any type of meaty foods, since black ghost knife fish are strictly carnivores.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 1 Helpful 10

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Tips

A UV sterilizer can prevent many diseases.

Thanks
Helpful 0 Not Helpful 0

Submit a Tip

All tip submissions are carefully reviewed before being published

Name

Please provide your name and last initial

Submit

Thanks for submitting a tip for review!

Warnings

Never use copper in a ghost knifefish tank.

Thanks
Helpful 7 Not Helpful 0
Don't have anything rough in your aquarium. Knifefish don't have scales and could get hurt on rough items.

Thanks
Helpful 8 Not Helpful 1

Expert Interview

Thanks for reading our article! If you’d like to learn more about fish and aquarium care, check out our in-depth interview with Craig Morton .

Log in

How to Care for a Black Ghost Knifefish

Steps

Providing a Good Habitat

Feeding

Community Q&A

Tips

Warnings

Expert Interview

You Might Also Like

About This Article

Did this article help you?

Quizzes

You Might Also Like

Featured Articles

Trending Articles

Featured Articles

Featured Articles

Watch Articles

Trending Articles

Quizzes

Explore Categories