Mantis Shrimp in an Aquarium

While investigating the mantis shrimp, we found mixed opinions about these marine animals. Some aquarists find them interesting and enjoyable pets, while others see them as a threat to any aquarium. Let’s explore their characteristics and nature so you can decide if you want to keep one.

What Are Mantis Shrimp?

Found in tropical waters worldwide, they belong to the phylum Crustacea, class Malacostraca, subclass Hoplocarida (meaning “armed shrimp”), and order Stomatopoda. Often referred to as stomatopods, they come in a wide variety of species. As carnivores, they will eat almost anything, making them expert hunters. They are solitary animals, and unless you have a large tank, they should be kept alone.

Mantis shrimp have two hunting styles: “spearers” and “smashers.” “Spearers” use a spear-like claw to silently stab soft-bodied prey, while “smashers” use a powerful, club-like claw to break or crush hard-bodied prey. “Smashers” have a strike force comparable to a .22-caliber bullet and are known as “thumb splitters.” It’s rumored that their strength is enough to crack aquarium glass!

Mantis shrimp are burrowers and create tubes or cavities in sand, rubble, or mud. They adapt to living in holes, cracks, or crevices in rocks, and can reside in snail or hermit crab shells. A mantis shrimp might unexpectedly appear in your tank by hiding on a live rock due to their excellent hiding skills!

Some mantis shrimp species can grow up to 12 inches long. A notable six- to eight-inch black and white striped species can be found on the mudflats in Hawaii, which should not be underestimated.

Common Sign of a Mantis Shrimp

When fish, crustaceans, and invertebrates start mysteriously disappearing from your aquarium, many aquarists suspect a mantis shrimp. While this is a key sign of their presence, other marine animals could also be the cause. Consider a mantis shrimp as a suspect, particularly if fish are disappearing, but thoroughly investigate other possibilities before jumping to conclusions.

Popping Noises: Mantis Shrimp vs. Pistol Shrimp

Some believe clicking, popping, or snapping sounds from your tank indicate a mantis shrimp. Others argue these noises suggest a pistol shrimp instead.

If you have a pistol shrimp, suspect it for the sounds. However, pistol shrimp are unlikely to attack or kill fish but may punch holes in hermit crab, snail, and other mollusk shells to feed.

As natural burrowers, mantis shrimp create tubes or cavities in sand, rubble, or mud. Look for holes or tunnels with mounds of sand or rubble outside them. Pistol shrimp also exhibit this behavior, so if you spot such a hole, dim the tank lights and observe what emerges.

Mantis Shrimp: Pest vs. Pet

In the aquarium hobby, mantis shrimp are often regarded as monstrous creatures. This reputation is understandable for aquarists who have lost valuable specimens to them.

However, if a mantis shrimp accidentally enters your tank with new live rock, it’s not surprising that it behaves as a carnivore. While mantis shrimp might seem monstrous, they are simply doing what they naturally do: hunt.

Some aquarists love mantis shrimp for their hardiness and ease of care. They aren’t picky about tank conditions, are easy to feed, and are affordable to maintain. However, this doesn’t mean their environment can be neglected. Proper care is essential, as with any marine animal.

Adding a mantis shrimp to a fish-only or reef tank is generally not advisable. Their aggressive and territorial nature means they are best kept alone, although several can coexist in a very large tank with ample space.

How to Remove Mantis Shrimp from an Aquarium

Removing a mantis shrimp is challenging and requires patience. If one method doesn’t succeed, try another.

• Force it out with a stream of water. If the shrimp resides in live rock, wait for it to enter its hole. Place the rock in a bucket with saltwater. Use a turkey baster or syringe to squirt fresh water into the hole. The shrimp should eventually emerge.
• Dunk the rock in fresh water. Dunk the rock in fresh water.** Submerge the rock in a bucket of fresh water, but use this method only if you’re not concerned about losing other marine life on the rock.
• Wait it out. Remove the live rock and place it in a dry container or sink. With patience, the mantis shrimp may emerge, but this method often requires persistence as the shrimp can be just as patient.
• Catch it at night with a net. Mantis shrimp are nocturnal, so they’re best caught at night in a dark tank. Wait patiently and quickly scoop them with a net when they’re away from their burrow.
• Use natural predators like triggerfishes to combat them.
• Buy or make a trap. Many commercial traps are available for mantis shrimp, or you can build one yourself.

What to Do With a Mantis Shrimp

Once you remove the mantis shrimp from your tank, you have several options.

• Keep it and provide it with a tank of its own to live in.
• Ask a friend if they want it. Some aquarists enjoy keeping mantis shrimp.
• See if a local fish store with take it. They might even pay you for it.
• Contact a public aquarium in your area.  They might be interested in having it.