What's a Mantis Shrimp?

Is having a mantis shrimp in your aquarium considered a pest or a pet?

Mantis Shrimp

Robert Marien / Getty Images

While investigating the mantis shrimp, we found mixed emotions about these marine animals. Some aquarists feel that they make an interesting, intriguing, and enjoyable pet to have in an aquarium, while others feel they are the total scourge of any aquarium. Let's take a look at their characteristics and nature to learn more about them; then you can decide for yourself if you want to keep one or not.

What Are Mantis Shrimp?

  • They fit into the Crustacea phylum in the class Malacostraca, subclass Hoplocarida (which means "armed shrimp"), and order Stomatopoda.
  • They are most often referred to as Stomatopods.
  • They come in what seems like an endless variety of species.
  • They are found in tropical waters worldwide.
  • They are carnivores and will eat just about anything and everything.
  • They are experts at catching and killing prey, being very clever, stealthy hunters.
  • They are masters at hiding.
  • They are not related to shrimp but are referred to as shrimp because of their front appendages and how they use them to capture food.
  • They are called a "Mantis" Shrimp due to the fact they resemble the appearance and have the same hunting characteristics of a praying mantis insect.
  • There are two hunting categories, the "spearers" and the "smashers." The "​spearers" use their spear-like claw to silently stab soft-tissued prey. The "smashers" use their forceful, club-like claw to hit, crack open or pulverize harder bodied prey. It is interesting that the power of the "smashers" appendage can produce a blow close to the power of a .22 caliber bullet and are notoriously known as "thumb splitters." It is rumored that because of the tremendous strength these animals have, they can crack aquarium glass. From a story about how a pet Mantis Shrimp broke 1/4 inch aquarium glass, that was posted in ​The Daily Mirror (a British Newspaper) on Friday, April 10, 1998, page 11, this documentation leads us to believe that this is possible.
  • These animals are burrowers and can create tubes or cavities in sand, rubble or mud.
  • They will adapt to living in holes, cracks or crevices in rocks, and may take up residence in snail or hermit crab shells as well.
  • They are solitary animals, and unless you have a VERY large tank, they should be kept alone.

The Mantis Shrimp is no wimp; some species can reach up to a length of about 12 inches. We find a very large six- to eight-inch, black and white striped species here in Moloka'i waters on the mudflats that are not to be taken lightly. We also have a two to three-inch green species that may be small, but still very powerful. So how does a Mantis Shrimp get into your tank, aside from intentionally putting one there? By hitchhiking in on live rock.

Disappearing Acts

  • When fish, crustaceans, and invertebrates begin to mysteriously disappear from your aquarium without a trace, the first assumption a lot of aquarists make is that a Mantis Shrimp is the culprit. Even though this is a prime sign that a Mantis Shrimp may be present in your tank, it sometimes can be a premature conclusion as well. There are other marine animals that can contribute to this same problem, as Scott Michael outlines in his Disappearing Fish Q&A article posted in the Aquarium Fish Online Fish Library. Do consider a Mantis Shrimp as the culprit, especially if fish are disappearing, but also investigate other possibilities thoroughly before you start driving yourself nuts looking for one.

Popping, Clicking and Snapping Noises

  • Some say when you hear clicking, popping or snapping noises coming from your tank, you have a Mantis Shrimp. Others say this is not so, that you have a Pistol Shrimp and not a Mantis Shrimp. From what we have found throughout our investigative research, with the resources provided below you can see this topic is widely debated.​
  • Albert Thiel's More On Mantis Shrimp response to questions asked about Pistol and Mantis Shrimps explains from his experiences the differences between how these two types of shrimp use their appendages for hunting. Both have the ability to make a popping or clicking noise but do so differently in their way.
  • From Lurker's Guide To Stomatopods, their sheds some more light on the popping noise debate, and includes information on the how do you tell if there's a Mantis Shrimp in your tank page differences between Pistol and Mantis Shrimps.
  • The Mantis Shrimp FAQ from Jeff Pfohl's Marine Aquaria Index contains some of the same content found in the "Mantis Shrimp are really cool" posting from The Krib, but once you get past the top section, you'll find all kinds of additional exchanges between hobbyists here. There are plenty of comments and debate on whether Mantis Shrimp have the ability to make clicking and popping noises or not, and it is a good reference for other information about these shrimp, such as how to care for them, remove them from an aquarium, and more.
  • From our own personal experiences, we would suspect a Pistol Shrimp before a Mantis Shrimp, because we have Pistols in our tank and hear these noises all the time. Pistol Shrimp are unlikely candidates for attacking or killing fish, but they will punch holes in hermit crab, snail, and other mollusks shells to kill and eat the animals in them.

Burrows, Holes & Substrate Mounds

Since these animals are natural burrowers, creating tubes or cavities in sand, rubble or mud, look for holes or tunnels in the substrate. These are usually accompanied by a mound of sand or substrate rubble piled up outside the hole. Pistol Shrimp have this character trait as well, so if you find a hole like this, just dim the tank lights and sit back to see what comes out. Our Pistol Shrimps like to burrow "under" things, rather than directly in an open space of the substrate.

Before Dr. Roy Caldwell consented to give us permission to use his Odontodactylus havanensis photo in this article, he asked us if it was going to be about them as pests or interesting pets. Having studied Stomatopods for thirty years, he stated that, "I find them far more interesting in an aquarium than most fish. The trick is finding the right species for the right tank." Dr. Caldwell has a deep respect for Mantis Shrimp, and he strongly feels they are wrongfully misjudged and misunderstood, which is quite true, so we can understand why Dr. Caldwell feels this way.

In the aquarium hobby, Mantis Shrimp are made out to be the worst, monstrous creatures that have ever inhabited oceans or aquariums. For those marine aquarists who have lost many valuable specimens to a Mantis Shrimp, you can see their point of view as to why they have this reputation. However, if a Mantis Shrimp is accidentally introducing into your tank while adding some new live rock, what do you expect from a carnivorous creature like this? Is it the shrimp's fault it ended up in your tank and began to eat everything in it? Mantis Shrimp may "seem" to be monsters, but they are just doing what they naturally do... hunt.

Some aquarists love Mantis Shrimp and enjoy their company, as you can read in this "Mantis Shrimp are really cool" posting from The Krib. "It doesn't take a rocket scientist to maintain mantis shrimps", says The Lurker's Guide To Stomatopods. They are hardy and difficult to kill, aren't picky about tank water conditions or filtration, are easy to feed and cheap to maintain. This is not to say that if you have one you should neglect their tank environment, but just to make the point that they are easy to care for and are not very demanding like a lot of other marine animals can be. Whenever you decide to keep any marine animal, the responsibility to properly care for it is expected. You, as their caretaker, should respect that!

Here is additional information contributed by Dr. Caldwell to learn more about Mantis Shrimp species identification and their characteristic traits.

The natural response from just about any saltwater aquarists that hears the words "Mantis Shrimp" is, GET RID OF IT, NOW! They are voracious killers and will eat or destroy all your tank inhabitants if not removed immediately. Yes, this is all true. Upon discovering you have a Mantis Shrimp in your tank it probably already has destroyed some tank inhabitants, and if not promptly removed, it will continue to do so until you can get it out of the tank. Don't panic. What has been lost is lost, and by taking action to remove it as soon as you can will help to prevent further losses. However, it shouldn't be any big surprise if you loose a few other critters in the process. Catching a Mantis Shrimp is not always a simple task, and often takes some time to do. Try to be patient, and don't get mad at the shrimp. It's only doing what it naturally does... hunt

The question of whether intentionally adding a Mantis Shrimp to a fish-only or reef tank is bad, the answer to this is an unequivocal, yes!. If you do put one in an aquarium with other animals, don't get mad at the shrimp if things start disappearing. If you decide you want to buy a Mantis Shrimp or keep one, because of its territorial and aggressive nature, it is best kept it in a tank by itself, but several may be kept together if you have a very big tank with plenty of room.

When a Mantis Shrimp is introduced into your tank by accident, by all means, you have the right to remove it. However, before we go into methods of removal, may we suggest you consider other options of what to do with it prior to catching it, other than killing it?

After an aquarist has been pinched, slashed and attacked while trying to remove a Mantis Shrimp from their aquarium, and lost many valuable inhabitants before being able to do so, the general consensus of what to do with it once you've caught it is, kill and dispose of it. However, as was stated earlier when it is accidentally introduced into an aquarium, it's not the shrimp's fault it ends up eating everything. It didn't ask to be put there, so why get mad at the shrimp for acting naturally? For these reasons, before catching and removing one, we ask that you please consider these other options first.

  • Keep it and provide it with a tank of its own to live in.
  • Ask a friend if they might want it. This might sound silly, but there are aquarists who love and enjoy keeping Mantis Shrimps.
  • You might be able to find a local fish store that likes them and may even buy it from you.
  • Check to see if a public aquarium in your area may be interesting in having it?

Now that you know the options, other than killing the shrimp, once you have decided what to do with it, its time to remove it from the aquarium.

First and foremost, whenever dealing with Mantis Shrimp, it is wise to ALWAYS wear a pair of heavy gloves! That said, here are methods you can use to remove an unwanted shrimp from your aquarium.

  • If you have found it has taken up residence in a piece of live rock, watch and wait patiently for it to go into its cavity (hole). Once it's in the rock, because your live rock may have other marine life on it, you do not want to lose, remove the piece of live rock and place it in a bucket or container with saltwater. Pick up the rock, and using a turkey baster or syringe, squirt fresh water into the hole. The shrimp should either come flying out of the hole, or eventually coming out after many squirts, and patience.
  • Use the same method mentioned above, but use carbonated water or club soda instead.
  • Dip or place the rock into a bucket of fresh water, but only use this method if you are not concerned about losing any other marine life that may be living on the rock.
  • You can remove the live rock and place it in a bucket, container, or just the sink without any water at all. With patience and baiting the Mantis Shrimp may crawl out on its own, but this does not always work well. The shrimp can be as patient and persistent as you, and it turns out to be a waiting game. You can see what we mean by reading Simmon Buntin's Strange Waves column article "Ye Olde Mantis Shrimp" from AquaLink. His story is a salty tale of monstrous proportions of how he battled against ridding his tank of one of these shrimp in various ways but finally won.
  • Mantis Shrimp are nocturnal feeders, so they are best caught out in the open at night in a dark tank. Once again, sitting, waiting, watching and moving quickly can work if you can catch them out in the open away from their burrow or cavity by scooping them with a net.
  • Use natural predators like Triggerfishes to combat them.
  • Buy or make a trap. There are many commercial traps on the market designed specifically for catching Mantis Shrimps, or you can build your own, like our DIY PVC Aquarium Trap.

When removing a Mantis Shrimp, it is not always an easy task. It takes patience, time, and if one method doesn't work, try another.