Mantis shrimp hunt... losing morale....

Antegon · Mar 22, 2018

Hey y’all,
So I’m 90% sure I have a mantis shrimp.
Facts -

Water Parameters are good and steady.

CUC do no survive in this tank. Once in a while a snail will stay at the top of the water line and hang for a few months. Hermits and Emeralds seem to have about a 50/50 shot.

It’s been established (the rock has, anyway) for 5/6 years, and the original owner for rock from whoever was giving rock away that day, and have has its fair share of hitchhiker issues since I adopted it last year.

I have, intermittently, heard a “tap tap tap” clicking near the end of the light cycle. It is rapid, and without pattern. Almost like sloppy Morse code.

The worst part - My neon dottyback has now not come back out from the rocks in 2 weeks. The damsels I would assume are too fast and the clown doesn’t leave her BtA forest.

I have tried the bottle traps, no takers.

Is there another way? I am building out a 75g (currently in a 55) and was planning on replacing and/or bleaching the rocks I do have. Def wanna start pristine after all these issues. Is there a way to remove the rocks you think there’s something in, and dip them or something so this fella will come out? It would be great to not kill it, but at the end of the day, he’s already cost a fair share in livestock lives.

Any advise beyond the bottle trap would be most appreciated. Thanks team!

ritter6788 · Mar 22, 2018

Hermit and snail shells broken or whole? If they are whole I would blame something else. The clicking could be a pistol shrimp. Mantis shrimp aren't always really shy. If you have one you would likely see it at feeding time.

enveeRF · Mar 22, 2018

I loose CUC all the time. Hermits kill snails, hermits kill each other. I also hear clicking sounds at times, most of the time it's a snail hitting the shell on the glass.

madweazl · Mar 22, 2018

Tapping/clicking noises imply a smasher (if mantis) and smashers dont take down fish. Most smaller species of mantis only go after very small CUC as well.

ThunderGoose · Mar 22, 2018

If you can pull the rock I heard that dipping in seltzer water will cause mantis to come out. I haven't tried it and I don't know what it would do anything else.

I have a mantis that I rarely see and I haven't lost many CUC. I lost a lot more when I had an aggressive hermit (Dexter has black and white legs and now lives in the refugium).

Joe Rogers · Mar 22, 2018

ritter6788 said:
Hermit and snail shells broken or whole? If they are whole I would blame something else.

I think that this would be your biggest clue if it was a mantis taking the CUC down. As was also mentioned, a smasher mantis would not take down a neon dottyback IMO. Can you post full params? An easy answer might be that your tank is running clean enough to not produce enough food for your CUC.

Antegon · Mar 22, 2018

Ok, cool! Thanks everyone.

The shells are whole, at least all the ones I see.

I would think the CUC has enough food. The water levels are good now, but they weren’t for a long time previously from before, so I still battle enough algae and things that I would have thought to be enough to feed the team. I don’t get those “CUC kits” the lfs will throw at you, Ive been trying to add slow to make sure this wasn’t the issue.

I will say there are 2 - 3 larger hermits that continue on. But I don’t think big enough to be killing snails and crabs. I didn’t know they did that honestly.

N02, PO - close to zero
Sal - 1.025
Temp - 78.5
Cal - 440
Mg - 1400
DKh - 11

I love the idea that this isn’t a crazy monster lurking and planning to kill the livestock for fun one by one, as my imagination has now lead me to assume, haha.

ThunderGoose · Mar 22, 2018

Antegon said:
Ok, cool! Thanks everyone.

The shells are whole, at least all the ones I see.

I would think the CUC has enough food. The water levels are good now, but they weren’t for a long time previously from before, so I still battle enough algae and things that I would have thought to be enough to feed the team. I don’t get those “CUC kits” the lfs will throw at you, Ive been trying to add slow to make sure this wasn’t the issue.

I will say there are 2 - 3 larger hermits that continue on. But I don’t think big enough to be killing snails and crabs. I didn’t know they did that honestly.

N02, PO - close to zero
Sal - 1.025
Temp - 78.5
Cal - 440
Mg - 1400
DKh - 11

I love the idea that this isn’t a crazy monster lurking and planning to kill the livestock for fun one by one, as my imagination has now lead me to assume, haha.

My murderous hermit isn't that big - he's definitely killed snails bigger than him and hermits of similar size so don't underestimate yours.

reef lover · Mar 22, 2018

Hermits are ruthless. And agreed mantis aren't shy you'd have seen him by now.

Antegon · Mar 22, 2018

Wow. Ok good to know. Should I be on the lookout for one who seems violent and remove?

Erica-Renee · Mar 22, 2018

I have had to relocate a few hermits to Life in the sump.I suspect its a combination of not enough food and becoming food is the demise of your CuC .

The whole Cleanup Crew is a must thing was Created by those who sell clean up crews.......Unless you are way over feeding you would have spotted a mantis by now as it appears you have been looking for something. I would say gorilla crab or something similar but that again is a stretch

Antegon · Mar 22, 2018

Ok thanks! Yeah I’ve heard gorilla crab before, but I had never seen a crab before I put the emeralds in. One that I see occasionally is way bigger than the other two and has really hairy legs, but looks exactly like the other emeralds, so I think I just was seeing what I’d been told to look for, yah know?
Three of the bigger hermits always huddle together up on this rock, I’ll watch them and see if there’s a bully or two in their ranks.
The only other oddity that I could think of, having no idea whether it’s related to this subject or not, but wanting to cover every base with anything I’m not familiar with just in case, is the little dirt piles. Here’s a rough picture. They look like doodle bug mounds (rolly pollys) just little piles of a grey dirt that is much finer in grain than the substrate, making it stick out.

This tank is a treasure trove of life you didn’t ask for haha. Thanks again everyone for the awesome feedback.

reef lover · Mar 23, 2018

I' thinking cuc feces?? Snail or hermit...

Antegon · Mar 23, 2018

reef lover said:
I' thinking cuc feces?? Snail or hermit...

It feels big for that. Like a dime in diameter. ...dimeameter? Unless they collect and pile it up for something?

It’s just so cool how may of these things could be so many different things. I mean what a headache haha but man what a constant adventure

reef lover · Mar 23, 2018

Hmm strange not sure....

Joe Rogers · Mar 23, 2018

Antegon said:
It’s just so cool how may of these things could be so many different things. I mean what a headache haha but man what a constant adventure

Right? That has to be one of my favourite parts of the hobby. You begin to realize that an established reef tank is an ecosystem and as much as we like to think of ourselves as its "keeper", there are unknown animals/communities living in our tanks that we may never even encounter.

Skygirl997 · Mar 23, 2018

I keep a mantis shrimp in my display (maroon Odontodactylus havanensis). He’s small, only two inches, and a model citizen. I feed him regularly to ensure he doesn’t turn to the dark side. My CUC is all intact, so it’s possible to keep one of these in your tank with your other friends.
Your sand piles do look like excavation sites from a mantis. Chances are good that’s his rock. Try to identify your mantis before you nuke your rock, you maybe able to keep your super cool hitchhiker (or sell it).
That being said, do have extra shells for your hermits? They need new shells to grow into, otherwise they will attack snails and other hermits for their shells. If you don’t have extra shells, go to your local craft store a buy a bag of shells in the size and shape of the shells your hermit is currently sporting. (It’s usually much cheaper than your LFS.)

Antegon · Mar 23, 2018

Skygirl997 said:
I keep a mantis shrimp in my display (maroon Odontodactylus havanensis). He’s small, only two inches, and a model citizen. I feed him regularly to ensure he doesn’t turn to the dark side. My CUC is all intact, so it’s possible to keep one of these in your tank with your other friends.
Your sand piles do look like excavation sites from a mantis. Chances are good that’s his rock. Try to identify your mantis before you nuke your rock, you maybe able to keep your super cool hitchhiker (or sell it).
That being said, do have extra shells for your hermits? They need new shells to grow into, otherwise they will attack snails and other hermits for their shells. If you don’t have extra shells, go to your local craft store a buy a bag of shells in the size and shape of the shells your hermit is currently sporting. (It’s usually much cheaper than your LFS.)

Thanks! That’s great to know about the shells, there don’t seem to be many in the substrate.
What would the mantis be excavating?
Is there any way to run a camera all night on that spot to see this thing? I’d assume the light needed for that would probably not help things.
I would love to know whatever this thing is so I could either give it a happy home or find it another one lol.
I will put shells in, give it a week or two, then attempt to add a couple of snails and see how they do.

Skygirl997 · Mar 24, 2018

My mantis prefers to make his home inside the live rock. He carves out little trails straight through the rock itself. My pistol shrimp, on the other hand, prefers to dig underneath the rock, making caves through the substrate and decorating/supported with shells (sometimes with live inhabitants) and small bits of rock underneath the rock structure. Try to figure out where the majority of the disturbance is coming from, underneath the rock or inside.

Also, a side note, it may not be an invert that is eating your CUC. I had a CUC massacre early in my reefing career. I blamed it on our Tiger pistol shrimp at the time. A year later the Tiger shrimp died, so I thought I could add some expensive hermits “Electric Blue Leg- $15/ea). They all disappeared within four days except for one. Turns out, my Pink Diamond Goby would attack any hermit or snail that wondered near its cave enterance. He would grab them by the legs and whip them out of their shells.

My mantis is out only during the day. He has a hole at the front of the tank and every night around tank bedtime he goes into his hole a blocks the exit with debris, sand, and bits of shell. By daylight his hole is uncovered and has the diameter of a pencil. I don’t know if all mantis shrimp are mostly diurnal, or I’ve just trained mine.