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Can You Keep Sea Urchins in Your Reef Tank? Facts & FAQs

Brooke Billingsley

By Brooke Billingsley

sea urchin underwater

If you have a saltwater coral reef tank and wonder if you can keep a sea urchin in the same tank, the short answer is yes. However, there are many species of sea urchin, and some are better suited to captivity than others.

If you would like to add one of these creatures to your tank but would like to learn more about them first, keep reading while we discuss what the sea urchin can do for your tank, which types will work best, diet, and more to help you make an informed decision.

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What Is a Sea Urchin?

The sea urchin is a bulbous animal with dozens of long, thin spikes covering its body, ranging from 1-4 inches across. There are more than 950 species of these slow-moving creatures in the ocean, and many species are being captive-bred, so it’s easier and less expensive to find one to keep as a pet. They are closely related to sea cucumbers and move using tiny feet with suction cups on the tip.

sea urchin on top of corals
Image Credit: Piqsels

Why Do I Want Sea Urchins in My Coral Reef Tank?

Sea urchins are good for your coral reef tank because they help keep it clean by eating the algae. A single specimen works much like the bottom feeders in freshwater tanks and will help you keep the water clear without chemicals. Many species are extremely colorful and will accent the coral in your tank.

How Large Does My Tank Need to Be?

One of the best things about sea urchins is that they don’t require much space. Most owners recommend one gallon of water for every inch the sea urchin will grow. Since most don’t get larger than 4 inches, you can usually keep several in your tank. Since they are voracious eaters, you may need to add algae supplements like kelp to your aquarium to make sure they have enough food.

sea urchin in underwater aquarium
Image Credit: sarangib, Pixabay

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Top 5 Sea Urchins for Aquariums

1. Blue Tuxedo Urchin

Blue Tuxedo Urchin
Image Credit: Vojce, Shutterstock

The Blue Tuxedo Urchin is a great choice for any aquarium. It has blue bands between multicolored spikes. It won’t harm your reef and is most active at night, preferring to hide during the day. However, it’s fun to watch when you see it, and it can grow to about 3 inches.

Most experts recommend one or two in a 10-gallon tank. The only downside to this species is that it might need calcium, magnesium, and other supplements.

2. Black Longspine Urchin

Black Longspine Urchin
Image Credit: Jung Hsuan, Shutterstock

As you might have guessed, the Black Longspine Urchin gets its name from its dark color and long, pointy spines. It’s one of the larger urchins and can often grow to about 10 inches in diameter. You can get the Longspine Urchin in other colors, too, including white, blue, and green. Since these urchins are so large, most owners recommend a minimum tank size of 20 gallons.

Despite their intimidating appearance, these urchins are peaceful and will not damage your reef.

3. Pencil Urchin

close up pencil urchin
Image Credit: 12019, Pixabay

The Pencil Urchin is one of the few sea urchins that have long blunt spikes. The urchin wedges these large spikes between rocks to keep it in place in high current water. These urchins are nocturnal and prefer shallow water but can live happily with your coral reef and are not aggressive toward other urchins or fish.

You can find them in the West Atlantic coastal regions, and you can keep one or two of them in a 10-gallon tank.

4. Shortspine Urchin

You can also call a Shortspine Urchin a Rock Burrowing Urchin due to the way it likes to bury itself under dead coral while it sleeps during the day. It’s a colorful urchin with deep red spines that typically grows to about 3 inches. It’s peaceful and won’t damage your reef.

Despite their smaller size, these urchins prefer to live in a 20-gallon tank with plenty of dead coral to bury themselves.

5. Royal Urchin

The Royal Sea Urchin is similar to the Blue Tuxedo Urchin and features similar banding. However, the Royal Urchin requires a larger tank size of 30 gallons to stay healthy. It’s easy to raise and peaceful toward other animals and coral.

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Final Thoughts

As you can see, not only is it possible to keep sea urchins in the same tank as your coral reef, but they can also help add more colors and variety. You can even add different species of urchins as most are peaceful. We recommend starting with the Blue Tuxedo or Pencil Urchin because these only require a small tank and are friendly toward each other and the reef.

We hope you have enjoyed reading this guide, and that it has helped answer your questions.

See also:

Featured Image Credit: Piqsels

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