Help, mantis shrimp sighted

[M. Tournesol]

Hip, hip, hooray for live rock 🎉. My 3 months of age 100% live rock started nano reef seems to still give me some surprises. After a mysterious crab (Xanthid?) observed 1 month ago and that I may have not succeeded to kill,
 
my tank offers me the true and only mantis shrimp sea predator.  (please 🙏🙏, don't give me an Bobbit Worm next)

 

It is true that such creature are fascinating, but I do have more love for my Stonogobiops nematodes / Alpheus randalli pair. The pair live under the orange circled rock, the mantis in the red circled one.

 

What should I do? The mantis is not a problem if it decides to not eat my pair, snails and feather dusters. I also plan to top of my stocking with a Yellow-Striped Cardinalfish.

Should I go panic mode and remove the rock that seems to be is home or just let it be?
If removing the stomatopod is the answer, what would be the step to do it and not have a rogue predator in my little salt puddle?

[M. Tournesol]

I decided to listen to an old post on another forum and make offering 🙇‍♂️ of food for the mantis.

Quote from the old post : " As crazy as it sounds, if you keep it fed and full , it won’t kill for food. “A fat mantis is a happy mantis”. "

I may deal with it if some of my precious snails disappear or in 1 year when I will move house.

 

If you have any advice (trap, optimal food offering, ... ), please comment 

[Clown79]

I love mantis shrimp but it is a living creature which isn't predictable.

 

Lightening fast, amazing eyesight.

 

I personally would trap it and keep it in its own tank.

[M. Tournesol]

On 4/8/2021 at 2:52 PM, Clown79 said:

I personally would trap it and keep it in its own tank.

I 100% agree, but I do not have the possibility to setup another tank this year. Even giving it seems difficult with France actual confinement. After traping it, it would need to go to stomatopod paradise 😢. If it behaves itself for 1 year 🙏, it may obtain a tank for himself as I wish to go bigger(tank) after moving home.

[Tired]

You could get a "breeder box" and hang it on the side of the tank. That's a mesh or plastic box that hangs in the tank, and you can put creatures in it. You could also try to see if you can find anyone else who'd like it.

 

Can you tell if the mantis is a smasher or a spearer? A smasher wouldn't be likely to go after a cardinalfish, especially not if well-fed, but a spearer might.

 

Your crab looks like a xanthid or stone crab, yes. Try a bottle trap or some shot glasses. Bottle traps you can look up online. Shot glasses should just be set so that they're leaned against the rock, with food in the bottom. The crab goes inside to get the food, and can't climb out because it can't climb slanted glass. 

[M. Tournesol]

On 4/8/2021 at 11:50 PM, Tired said:

Can you tell if the mantis is a smasher or a spearer? A smasher wouldn't be likely to go after a cardinalfish, especially not if well-fed, but a spearer might.

I am 70% sure that it is a "smasher" 🙏. It came from live rock and lives in a rock wish is a "smasher" characteristic. Locking at "roy's list" and knowing that it has blue antennal scales (I observed blue reflexion), it could be: 

- Gonodactylaceus glabrous
- Gonodactylaceus ternatensis

which belong to a genus containing only smasher mantis.

[aclman88]

Lucky! I  would love a free mantis! But, I understand that might not be the case for you  since you can set up a second home if it goes Freddy Krueger on your livestock

[Jungle_vip]

I had a mantis hitch in live rock once. I removed the rock and put it in its own tank. 10 Gallon. One week later around 2 am a loud crack woke me out of my sleep. Turned light on and tank was busted and all the water on the floor. That would be my main concern but that’s me with my experience. Thumbs down for me in my tank.

[Clown79]

3 minutes ago, Jungle_v_i_p said:

I had a mantis hitch in live rock once. I removed the rock and put it in its own tank. 10 Gallon. One week later around 2 am a loud crack woke me out of my sleep. Turned light on and tank was busted and all the water on the floor. That would be my main concern but that’s me with my experience. Thumbs down for me in my tank.

Ya, thats the concern with mantis, apparently acylic tanks are best for mantis

[Jungle_vip]

11 minutes ago, Clown79 said:

Ya, thats the concern with mantis, apparently acylic tanks are best for mantis

Why were you not there for me 17 years ago? Lol

[Tired]

How big was it? That's a really rare thing, a mantis actually breaking a tank. Mostly it's just fearmongering. Little bitty ones aren't going to break anything. 

 

But yeah, acrylic won't shatter like that. It's flexible, it wobbles instead of breaking. 

[Broseff]

Any update? I think I just found one in one of my rocks and idk what do about it.

[Tired]

Catch it in a bottle trap and put it in a container where it won't die, then see if you can find someone who wants it. If not, humanely kill it. I recommend clove oil to humanely kill unwanted hitchhikers, since you should have it on hand anyway for euthanasia of suffering, dying fish. Health food stores should have it, or you can get it online pretty cheap, and you can read online how to use it.

 

Preferably, though, rehome it. Ask on here, on a local aquarium forum if you have one. Heck, if it's colorful, ask your LFS if they want it. They're novelties, and unusual to find for official sale. 

[Jungle_vip]

+1 for capture and rehome. Someone will def want it.

 

@Tired it was about 5” long or so. Only saw it once out of its hole. 17 years ago so it’s been awhile. I worked at a reef store in college and acquired it from there. I’ve never came across anyone else who has had it happen. Total bummer. I was so excited to have one. 

[Broseff]

4 hours ago, Tired said:

Catch it in a bottle trap and put it in a container where it won't die, then see if you can find someone who wants it. If not, humanely kill it. I recommend clove oil to humanely kill unwanted hitchhikers, since you should have it on hand anyway for euthanasia of suffering, dying fish. Health food stores should have it, or you can get it online pretty cheap, and you can read online how to use it.

 

Preferably, though, rehome it. Ask on here, on a local aquarium forum if you have one. Heck, if it's colorful, ask your LFS if they want it. They're novelties, and unusual to find for official sale. 

Sounds, good but I have a tiny tank and I don't think I can fit a bottle in it. 

 

Any idea how to get it out of the rock? I could probably pull the rock out (I'd need to put it back though, it may have other inverts living it in that I want to keep in the tank). 

[aclman88]

You could put it in hyposalinity. Fill a bucket with lower than normal salinity and the inverts should fall off or escape the rock. Then you can pick and choose what to keep. These are the instruction from KP aquatics for their live rock. 

[Tired]

Small bottle? 
 

How sure are you that it's a mantis, and not a pistol? 

 

You could put the rock in a bucket of water with an airstone, and trap the mantis out of there with a bottle instead. 

 

If you go with hyposalinity, I suggest doing it with the rock in a net. Then you can quickly lift the net full of critters into a container of normal salinity, and pick through them for what you want, instead of having to try to catch the beneficial things out of a hyposalinity bucket before they die.

[M. Tournesol]

No update one the mantis (It only "killed?" a sick/dying feather duster worm ;(, but no snails death). But I did capture "mister crab".
I would be happy to learn what it is. If it is a reef safe crab, i will put it back in the aquarium. If not,🔨💀

 

[M. Tournesol]

I am voting for xanthique crabs (Platypodia eydouxi?). Not a good news for him 😕. Sad, he is so cute.

 

[Tamberav]

Perhaps a dedicated pest tank? 😄

[M. Tournesol]

Not possible and too late. I did give him a quick death.

 

Image of the dead crab:

Spoiler

 

It is strange that I decided to keep the mantis but not the crab...

It may be the internet saying that crab should never be trusted.

[Clown79]

2 hours ago, M. Tournesol said:

Not possible and too late. I did give him a quick death.

 

Image of the dead crab:

  Reveal hidden contents

 

It is strange that I decided to keep the mantis but not the crab...

It may be the internet saying that crab should never be trusted.

The crab would have been mantis dinner eventually

[DaJMasta]

I recently removed three mantises from my tank which came in on about 30lbs of live rock, and the trick for me was to find out which piece of rock they were in, take the piece of rock out, and put it in a bucket with basically no water.  Wait a minute or two, then add water and swish around.  Often they'll run out of the rock to try to find another spot, then you pull the rock and they're caught and in the bucket.

Otherwise, trapping works, but they basically ignore food that isn't moving.  They will eat mysis and most meaty foods, but to get their attention it really has to be moving, or at least, you need to have food nearby and then move something in front of them.  Just flow moving it around will suffice, but if you feed with powerheads off, you could try a  moving piece of food at the end of a trap, or you could try sort of 'chumming the water' in the trap, then moving something else at the end of it, and they will spot it an pursue.

They are very inquisitive creatures, and while they are usually timid they can be very bold as hunters, so you can sort of lure them into coming out.  Mine seemed to be most active from midday to near lights off, but almost never ventured out at night - very different from many critters in a tank.

[Tired]

Yeah, definitely not a reef-safe crab. The big pinchy ones like that will eat anything they can get. Kudos for killing it quickly, at least- a lot of pests don't even get that much. 

[aclman88]

13 hours ago, DaJMasta said:

They will eat mysis and most meaty foods, but to get their attention it really has to be moving, or at least, you need to have food nearby and then move something in front of them.

Agreed. @DaJMasta was kind enough to send me one of his that he trapped. It’s currently in an acclimation box but I kept the little plastic cage he was mailed in which he didn’t venture far from. It takes frozen but I have to use tongs directly in front of it.

 

I have had luck with other shrimp by using a plastic bottle with the top cut off and inverted. I also included a small hole near the back of the bottle so I could use a Turkey baster to blow water in the bottle and get the frozen food blowing around inside. I also found that sardines worked well because they are chunkier and sit longer in the bottle. Plus the juices were very appetizing for the shrimp.