Answering from the bottom up:
Mantis shrimp can live with soft corals. Hard corals may be smashed by smashers.
No dosing. When the mantis shrimp molts, you must keep the tank parameters as stable as possible.
Mantis shrimp need subdued lighting. Dr. Roy says that strong lighting is possibly linked to shell disease in O. scyllarus.
Here's an extract from my article: (I would have posted the link but I think Reef Central doesn't let people post links)
Introduction
I'm guessing that you have decided to research Stomatopods because you have seen a video on Youtube of them hunting or because you have just found one in your live rock. Mantis Shrimp, which I am going to call mantarids for the rest of this article, are one of the hardiest saltwater animals available. They make very interesting and interactive pets, and are great for hobbyists, especially those new to Saltwater who have just made the jump from advanced freshwater aquaria.
For those of you who have found one in your live rock and have decided to keep it, contrary to popular belief, they are not woe to your painfully established reef system when introduced to your aquarium as hitch hikers in live rock. Although they potentially could smash up hard corals and kill a couple of fish, depending on your stocking system, they can become the centrepiece of your former coral-only system. Forget damsels, tangs and boring fish for the moment. If your hitchhiker has hunted and killed your lovely expensive tang/angel, it serves you right for choosing such a fish over something from the boxfish/canthigaster/diodon group of fish. Actually, I'm just kidding...
To bust another myth, neither are they evil hunters who devastate your cleanup crew and kill your favorite six line wrasse. In fact, my well fed mantarids have failed to even try to hunt a fish, including my P. ciliata. I have kept damsels and fast moving non-benthic fish with all my mantis shrimp successfully. In fact, I found my damsels rather pesky when they started stealing food meant for my mantis shrimp right from under their noses. My damsels have since been fed to my Pacman frog. Sorry, damsel lovers.
Do you want a mantarid?
Mantarids are active, intelligent creatures that need daily attention.(including basic aquarium maintenance such as emptying the protein skimmer). They are very undemanding in their husbandry, but if you keep them properly, they are sure to bring you endless entertainment with their antics and feeding habits.
They need daily care. This includes feeding it and while waiting for it to finish hunting and dining, emptying the protein skimmer (if you have one) checking on it's tankmates, if any, and other general maintenance. Going on vacation for more than 7 days will be a problem (but it would be for any saltwater system with anything more delicate than damsels and clownfish)
They need live food. You cannot expect them to eat the little pellets that your "nemo" eats. You HAVE to provide them with something appropriate at least once a week (I'll go into detail later)
Be prepared to let them take part in the decisions when aquascaping. I know you want to follow Amano-san's rule of having the centrepiece (in our case the mantarid burrow) two-thirds of the tank length from one end, but sometimes your mantis will decide to dig his cave at the back, behind the live rock. DON'T dig him out and jam him into the PVC tube you want him to live in, or it will cost you a month of distrust before he even dares to leave his burrow when you are watching.
Be willing to have a boring, empty water column. I know I just told you that most smashers can be kept with pelagic fish, but some mantarids (like my old peacock mantis, Samiera) like to go after the fish. It really depends on your individual pet's personality. Just observe, observe and observe and come to a decision. Actually, that isn't what I do. I put the mantis into a tank which already has fish. 100% success rate. No fish deaths. My G. glabrous is actually living with two benthic gobies, which were introduced into his tank after his molt.
If you want a mantis just because you like to see it hunt, it MAY get boring. If you aren't fascinated by their intelligence and in-times-of-peace behavior, please rethink.
That's about it, really. If you have passed this test (without cheating yourself), you are probably ready to read on about Stomatopod Care.
What size tank do I need for my mantarid?
It depends. It really does. You have to take into account the full size of the stomatopod in question. Decide what species (or genus at least) you are looking for. Most Gonodactylus species will live in a 10 gallon for life. Some small Odontodactylus species (O. havanensis, O. brevirostris) need only 5 gallons. Large Odontodactylus species (O. scyllarus, O. cultrifer) need a tank closer to 40 gallons. I actually think that for all smashers, you should provide a tank at least five times as long, three times as deep and twice as tall as the animal's adult length. This doesn't apply for large burrow-dwelling spearers such as L. malculata, though. Such animals need a tank around twice as long, twice as deep and three times as tall as the animal's adult length. Reclusive species will need less room. Active species such as O. scyllarus and P. ciliata will need as much room as you can give.
How do I set up a proper environment for my mantarid?
These animals demand very little. Generally, they aren't too fussy about their surroundings and will adapt to what they are introduced to. A smasher needs around 0.75 - 1x as deep a substrate bed as their length. For example, a 3 inch mantarid will need 2.25-3 inches of sand. Burrow-dwelling spearers need a deep sand bed twice their adult length I recommend aragonite as a substrate, followed by a scattering of crushed coral. The grade of the crushed coral will depend on the size of the mantis. I think that you should use bits that are approximately half the size of your mantarid's telson.
The mantis now needs a site to make a burrow. You can provide this in two ways. The easiest is to buy a PVC or ABS pipe that is 1.5 times the diameter of your mantis and twice as long. Position this in your tank (seal one end and stick it into the substrate) and hope your mantis will set up camp there (instead of digging a burrow in the back corner). The second option is to add some live rock to the tank so that the animal can either smash a burrow in the rock itself or dig a burrow in the substrate under the rock. This is risky, as the rock could collapse on the animal.
Since you've come this far, why not put some finishing touches in? Add some further passageways for your mantis to move about in by drilling holes in the live rock. Add more sheltered areas (live rock is good) or if your mantarid is green colored, consider adding macroalgae to the tank to make it more comfortable.
What about tankmates?
Again, it depends. Mantis shrimp have individual personalities, and not every mantis shrimp will serial kill every single tankmate it is given. It is most advisable not to have any fish with your stomatopods. This is more for the sake of the stomatopod than for the fish. Stomatopods tend to be alot less shy when they have a tank to themselves. I know this from first hand experience. However, if you must keep tankmates with yours;
Smashers and Pseudosquillas
Choose pelagic, fast-swimming fish such as clownfish, damsels or dwarf angels. Don't keep benthic fish such as gobies or dragonets with a mantis shrimp because they are more likely to be detected and killed. Actually, I have never had a smasher kill a fish in my care. Obviosly, hardshelled crustaeceans will not work. Hermit crabs, crabs, snails and urchins are usually destined to be food if placed in a mantis shrimp tank. Shrimp too, eventually. Soft corals might work, but hard corals stand a chance of being smashed.
Spearers
Fish are not going to work, full stop. Fish will definately be viewed as prey. Hermit crabs will stay alive, as long as they do not leave their shells. Crabs may die if the stomatopod learns to strike at their soft undersides. Shrimps will not work. Sessile invertebrates usually work.
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