A few weeks in, I'm already starting to regret getting a mantis shrimp

[Latte]

Right, my water quality issues seem to finally be under control. I won't make any sudden moves and will keep testing, but ammonia is barely detectable and nitrites are down to 0.2ppm from a high of 1.5, nitrates down to 25ppm from a high of at least 100 so I definitely seem to be on the back end of the cycle.

Oatmeal has been more active lately than when I started this thread, though still not as visible as I'd like - I probably see her for about 30-60 minutes a day poking her head out, and maybe 5 minutes she's roaming the tank which is is great compared to where I was before.

I think I want to have one more go at getting her to make friends with some fish. I know it's risky, and if it doesn't work out then I'll make a decision on whether I want to find her a new home but if it works I think I'll be happy with this tank for the long term. I've found a fellow reefer nearby who's willing to take the fish if I feel like they're imperilled and need to rehouse them.

So here's my thinking... I don't want to buy lots of fish at once because it seems riskier in all sorts of ways - more for Oatmeal to try to catch, more risk the fish don't get along with each other, water quality issues, more risk of disease, more money wasted on fish I could be giving away a few days later and so on. However, I've read over and over that you should add your most aggressive fish last, and yet it seems like my best chance at success with this is to choose fast swimming aggressive fish. I figure if she attacks a six line wrasse there's really no point in trying anything else after that point, but if I put that fish in on it's own, any other fish might be under threat from the wrasse. Therefore I'm thinking of doing either a six line wrasse and a yellow tail damsel at the same time, and seeing Oatmeal gets on with those two for at least a couple of weeks before trying anything else. If Oatmeal lets me I'd love to get to about 6 fish in total, but I'd be happy if I have to stop at two or three.

What I'm thinking of doing is experimenting over the next few days with feeding her to the point where she starts rejecting food so that I know how big her appetite is, then keeping the food at that level for the time being. I figure that way if she attacks the new fish I'll know it isn't because she's hungry, and it reduces the chance of her attacking in the first place.

Grateful for any thoughts on the strategy here, and whether the choice of fish is optimal. I'm obviously limited to what species I can get my hands on in the UK (ideally from my preferred LFS) and I'd prefer to err on the side of cheap and easy species, but the priority is obviously going to be that they're fast enough to evade Oatmeal's murderous clubs and territorial enough not to be too stressed by her.

I would stray away from using prime to 'detoxify' the water - I don't think that's how it actually works, despite their claims. This thread gives one example of how that just isn't how it works, and is aligned with my experiences (and also what intuitively makes sense to me).

In my personal opinion and experience (please feel free to share if you disagree) I think in a tank that size, with a mantis already and the type of fish you can actually add, the order of addition isn't as important. Mantis are already a heavy bioload, I don't think you'll be able to add too many fish, and the fish you are adding are likely to be both aggressive and able to hold their own no matter the order.

The strategy of overfeeding the mantis first makes good sense to me. I'd also recommend adding them at night or when the mantis isn't active. If you visibly add it in a way that the mantis associates with how you add fish, my experience is that you're far more likely to encounter issues. Maybe the use of an acclimation box is a good idea here? The mantis might begin to consider the fish as a part of its environment rather than food? Unsure.

I'd also echo waiting a while to add fish until the nitrites and ammonia are entirely gone and strongly encourage you to try get some rock rubble from a dark area of someone else's established sump, and add it to yours in a dark area. This should help with filtration a lot and likely help prevent issues in further. Also buy a few big bottles of pods and dump them in now if you want to prevent further issues down the line IMO

 

[wwarby]

Thanks @nmotz and @Latte

Regarding the Seachem Prime, I did look into it when you originally suggested it @nmotz and I read a couple of online reviews which in a nutshell seemed to be saying that whilst Seachem has a good reputation and most of it's claims are testable, the claim about detoxifying ammonia and nitrites is difficult or impossible to verify independently because it's effects don't show up in tests. I resolved to discuss it with my LFS on my next trip up there, but I have to admit I'm suspicious - it sounds like a bit of a snake oil remedy to me.

Also Oatmeal seems to have been totally unfazed by my apparently toxic water chemistry, having eaten well throughout and aside from spending more time in her burrow than I would like, showing no signs of distress as a result. I've been watching carefully for signs of shell rot and I'm pretty sure there is none. Opinions do seem to vary considerably on how hardy mantis shrimps are, and whilst I obviously accept she should never have been put in an uncycled tank, she seemed to have weathered the storm.

I'm not in a massive rush to get fish into the tank, just readying a strategy in my head at the moment. I want to experiment with feeding amounts first anyway. I want to test @nmotz' theory about whether she becomes lazy and more hidden when better fed, because I can always reduce the feeding again from that point.

I'll keep monitoring levels and wait until the water quality is completely under control before I make any changes, as you both suggested. That seems sensible. Also I think she might be getting ready for a molt. Last night she piled rocks in front of one of the entrances to her burrow, although she's knocked them over this morning. I'll keep an eye on that. If the water quality is up to snuff, would it be wise to add fish whilst she's molting? Just wondering if that would let them establish themselves for a few days whilst Oatmeal is hidden away.

Oh, and regarding the rock rubble, I have some live rock in my cannister filter (and a big piece in the display tank) which I bought from the LFS - I suspect that more than anything else is what got my nitrite levels to come down. I do want to get a bit more rubble as I have space for a bit more in the filter, but I bought about 5lbs of if I think, so there's a decent amount already (and it definitely is real live rock from the sea).

@Latte, could you elaborate on the bottled pods idea? What would that do for my system exactly? I've already put three bottles of bacteria in the tank so far over recent weeks, but I'm assuming you're talking about copepods which are a different thing right?

 

[Tired]

Copepods are tiny crustaceans, so they're definitely not the same as the bacteria. They feed on detritus and algae, and their presence is important for preventing pest algae blooms. A bottle of them is probably a good idea, as I'm not sure how many pods would have made it out of the canister filter from being put in there with the live rock.

 

[wwarby]

Copepods are tiny crustaceans, so they're definitely not the same as the bacteria. They feed on detritus and algae, and their presence is important for preventing pest algae blooms. A bottle of them is probably a good idea, as I'm not sure how many pods would have made it out of the canister filter from being put in there with the live rock.

Thanks - I’ll ask for a bottle of them next time I’m at the LFS. I do also have a big chunk of live rock in the display tank so if there were any copepods on that I might have a few in there by now, but I guess it can’t hurt to get more.

 

[Latte]

Thanks @nmotz and @Latte

Regarding the Seachem Prime, I did look into it when you originally suggested it @nmotz and I read a couple of online reviews which in a nutshell seemed to be saying that whilst Seachem has a good reputation and most of it's claims are testable, the claim about detoxifying ammonia and nitrites is difficult or impossible to verify independently because it's effects don't show up in tests. I resolved to discuss it with my LFS on my next trip up there, but I have to admit I'm suspicious - it sounds like a bit of a snake oil remedy to me.

Also Oatmeal seems to have been totally unfazed by my apparently toxic water chemistry, having eaten well throughout and aside from spending more time in her burrow than I would like, showing no signs of distress as a result. I've been watching carefully for signs of shell rot and I'm pretty sure there is none. Opinions do seem to vary considerably on how hardy mantis shrimps are, and whilst I obviously accept she should never have been put in an uncycled tank, she seemed to have weathered the storm.

I'm not in a massive rush to get fish into the tank, just readying a strategy in my head at the moment. I want to experiment with feeding amounts first anyway. I want to test @nmotz' theory about whether she becomes lazy and more hidden when better fed, because I can always reduce the feeding again from that point.

I'll keep monitoring levels and wait until the water quality is completely under control before I make any changes, as you both suggested. That seems sensible. Also I think she might be getting ready for a molt. Last night she piled rocks in front of one of the entrances to her burrow, although she's knocked them over this morning. I'll keep an eye on that. If the water quality is up to snuff, would it be wise to add fish whilst she's molting? Just wondering if that would let them establish themselves for a few days whilst Oatmeal is hidden away.

Oh, and regarding the rock rubble, I have some live rock in my cannister filter (and a big piece in the display tank) which I bought from the LFS - I suspect that more than anything else is what got my nitrite levels to come down. I do want to get a bit more rubble as I have space for a bit more in the filter, but I bought about 5lbs of if I think, so there's a decent amount already (and it definitely is real live rock from the sea).

@Latte, could you elaborate on the bottled pods idea? What would that do for my system exactly? I've already put three bottles of bacteria in the tank so far over recent weeks, but I'm assuming you're talking about copepods which are a different thing right?

Honestly the more I research it the more amazed I am by how important these micro crustaceans are. I struggled with Dinos for maybe 4-5 months, tried raising nutrients, UV, silicate dosing, blackouts, copious amounts of bottled bacteria etc. What finally worked in the end (and perhaps in combination with the rest of course) was an absurd amount of copepods. Gone almost overnight. I would recommend buying a lot, like a LOT of copepods for your tank and it will likely prevent some major issues in future.

As you set up your tank, there's a bunch of small organisms fighting for dominance. Before they reach an equilibrium, you want to give the ones you want to win an upper hand. Dose like $150-200 of pods now and save yourself a ton of future headaches IMO. They're usually found online, but you can sometimes find LFS that have bottles (generally from the online providers).

On Prime, that fits my thoughts exactly to be honest. I would also be hesitant about advice from LFS, some are very good and very knowledgeable, but, in my experience, the vast majority hang onto weird old ideas or misunderstand things frequently as the best interpretation, and are just simply overselling you at worst. I'm biased as I'm giving you this advice, but reef2reef generally is a much better source of reliable advice in my experience.

On the sturdyness of mantis, I believe the point of concern is around their moulting and this is where most mantis die. As they get older and bigger the moulting process is more stressful, longer, and more dangerous. I wouldn't add aggressive fish during this time as it could further stress out oatmeal. It will likely take some time, but be patient, and do not disturb the shrimp during the moult.

Finally, I definitely notice my mantis being far more active when she's hungry, I think you'll find similar results. Overall it's probably healthier for mantis to not become too lazy or overfed, they're super intelligent and investigating the tank for food seems to be very engaging for them, but I'm far from an expert on invert nutrition. And obviously you need to balance this with keeping the mantis well fed enough to be healthy.

 

[Tired]

Probably don't even need that many pods. They might already have come in on the live rock, but if not, a bottle of mixed pods will do the trick just fine. They'll multiply. No need to bomb the tank with pods when there isn't currently a problem.

OP- is the mantis named Oatmeal because of that one comic by that Oatmeal guy about the mantis shrimp? Just realized the connection.

 

[wwarby]

Probably don't even need that many pods. They might already have come in on the live rock, but if not, a bottle of mixed pods will do the trick just fine. They'll multiply. No need to bomb the tank with pods when there isn't currently a problem.

OP- is the mantis named Oatmeal because of that one comic by that Oatmeal guy about the mantis shrimp? Just realized the connection.

Yep, that's why she's named Oatmeal It's an homage to the reason I'm obsessed with mantis shrimps in the first place - I have a poster of that comic in my bathroom!

 

[wwarby]

Honestly the more I research it the more amazed I am by how important these micro crustaceans are. I struggled with Dinos for maybe 4-5 months, tried raising nutrients, UV, silicate dosing, blackouts, copious amounts of bottled bacteria etc. What finally worked in the end (and perhaps in combination with the rest of course) was an absurd amount of copepods. Gone almost overnight. I would recommend buying a lot, like a LOT of copepods for your tank and it will likely prevent some major issues in future.

As you set up your tank, there's a bunch of small organisms fighting for dominance. Before they reach an equilibrium, you want to give the ones you want to win an upper hand. Dose like $150-200 of pods now and save yourself a ton of future headaches IMO. They're usually found online, but you can sometimes find LFS that have bottles (generally from the online providers).

I'll do a bit of research on this as it's the first time I've heard the suggestion. I've no reason to think it's a bad idea, but $200 is not an insignificant amount of money to me so I'd want to be on pretty solid ground that I'm not just chucking money at a problem I don't currently have.

On Prime, that fits my thoughts exactly to be honest. I would also be hesitant about advice from LFS, some are very good and very knowledgeable, but, in my experience, the vast majority hang onto weird old ideas or misunderstand things frequently as the best interpretation, and are just simply overselling you at worst. I'm biased as I'm giving you this advice, but reef2reef generally is a much better source of reliable advice in my experience.

Yeah, this is a problem I've run into a lot. The LFS staff tell you to be wary of forum advice and the forum advisers tell you to be wary of the LFS staff. The YouTubers tell you to be wary of both, and everyone tells you to be wary of the YouTubers. LFS staff also tell you to be wary of advice from competing LFS staff . I've learned that advice differs wildly on many topics, so to the extent possible I try to absorb taking a broad sample of opinions and weight them based on perceived relevant experience and reputation to find consensus. For example a lot of people who have never owned a mantis shrimp (and some that have) will tell you they will kill everything in your tank, but there is plenty of hard evidence to the contrary.

My first LFS told me to fast cycle my tank with bottled bacteria with the mantis shrimp in it. They also sold me a UV steriliser (utterly unnecessary for my setup as far as I can tell), a cannister filter (widely considered the worst filtration mechanism for marine setups), a hopelessly inaccurate digital salinity meter instead of a refractometer and a test kit that has a poor reputation. I have cut ties with them and started using a local place which seems to be widely reputed to be one of the best in the country (Advanced Aquarium Consultancy in Harlow). They seem much less interested in selling my random stuff I don't need, and so far the advice they've given me has borne out as accurate. I'll always need to balance what they're telling me against competing opinions and especially where mantis shrimps are concerned I value the advice on forums from people who have actually kept them more than the LFS, but I definitely want to keep them included as part of my information diet for now.

On the sturdyness of mantis, I believe the point of concern is around their moulting and this is where most mantis die. As they get older and bigger the moulting process is more stressful, longer, and more dangerous. I wouldn't add aggressive fish during this time as it could further stress out oatmeal. It will likely take some time, but be patient, and do not disturb the shrimp during the moult.

Yeah, I'm definitely worried about her first molt. @nmotz thinks the burrow I've built is too narrow because she won't be able to jack-knife inside it whilst molting, and he may well be right. Her behaviour makes me think she wants the burrow to be bigger - she regularly hits the inside of it and occasionally seems to try to make a different burrow (which is impossible with my aquascape). Fixing it now though would be very difficult, requiring all the rock to be removed and reshaped around a bigger burrow and I suspect I'd be more likely to kill her or crash the tank by doing that than hoping she can molt in the existing burrow.

Finally, I definitely notice my mantis being far more active when she's hungry, I think you'll find similar results. Overall it's probably healthier for mantis to not become too lazy or overfed, they're super intelligent and investigating the tank for food seems to be very engaging for them, but I'm far from an expert on invert nutrition. And obviously you need to balance this with keeping the mantis well fed enough to be healthy.

This does make sense and I need to take it seriously. The point of the tank is to have a mantis shrimp in it - fish are a side show for when the main star (Oatmeal) is in her dressing room. If I overfeed Oatmeal as a tactic to keep the fish alive and she becomes more reclusive as a result I've done myself no favours whatsoever. Perhaps I should just take my chances, keep the feeding at current levels and hope she just doesn't bother the faster fish.

Anyway, I'm gonna hold steady for the next few days or weeks, watch to see if she looks like she's gonna molt, keep tracking my levels and only when I'm sure it's the right time, then I'll try a couple of fish and cross my fingers for them.

 

[Bhor217]

I'll do a bit of research on this as it's the first time I've heard the suggestion. I've no reason to think it's a bad idea, but $200 is not an insignificant amount of money to me so I'd want to be on pretty solid ground that I'm not just chucking money at a problem I don't currently have.


Yeah, this is a problem I've run into a lot. The LFS staff tell you to be wary of forum advice and the forum advisers tell you to be wary of the LFS staff. The YouTubers tell you to be wary of both, and everyone tells you to be wary of the YouTubers. LFS staff also tell you to be wary of advice from competing LFS staff . I've learned that advice differs wildly on many topics, so to the extent possible I try to absorb taking a broad sample of opinions and weight them based on perceived relevant experience and reputation to find consensus. For example a lot of people who have never owned a mantis shrimp (and some that have) will tell you they will kill everything in your tank, but there is plenty of hard evidence to the contrary.

My first LFS told me to fast cycle my tank with bottled bacteria with the mantis shrimp in it. They also sold me a UV steriliser (utterly unnecessary for my setup as far as I can tell), a cannister filter (widely considered the worst filtration mechanism for marine setups), a hopelessly inaccurate digital salinity meter instead of a refractometer and a test kit that has a poor reputation. I have cut ties with them and started using a local place which seems to be widely reputed to be one of the best in the country (Advanced Aquarium Consultancy in Harlow). They seem much less interested in selling my random stuff I don't need, and so far the advice they've given me has borne out as accurate. I'll always need to balance what they're telling me against competing opinions and especially where mantis shrimps are concerned I value the advice on forums from people who have actually kept them more than the LFS, but I definitely want to keep them included as part of my information diet for now.


Yeah, I'm definitely worried about her first molt. @nmotz thinks the burrow I've built is too narrow because she won't be able to jack-knife inside it whilst molting, and he may well be right. Her behaviour makes me think she wants the burrow to be bigger - she regularly hits the inside of it and occasionally seems to try to make a different burrow (which is impossible with my aquascape). Fixing it now though would be very difficult, requiring all the rock to be removed and reshaped around a bigger burrow and I suspect I'd be more likely to kill her or crash the tank by doing that than hoping she can molt in the existing burrow.


This does make sense and I need to take it seriously. The point of the tank is to have a mantis shrimp in it - fish are a side show for when the main star (Oatmeal) is in her dressing room. If I overfeed Oatmeal as a tactic to keep the fish alive and she becomes more reclusive as a result I've done myself no favours whatsoever. Perhaps I should just take my chances, keep the feeding at current levels and hope she just doesn't bother the faster fish.

Anyway, I'm gonna hold steady for the next few days or weeks, watch to see if she looks like she's gonna molt, keep tracking my levels and only when I'm sure it's the right time, then I'll try a couple of fish and cross my fingers for them.

Best of luck and way to go persevering. I've kept Peacock Mantis's for years, including when I was just restarting in the hobby. They are pretty resilient to water changes. Cycling the tank will help with keeping it stable, but the Mantis should be fine through the cycling process.

I created a capital J PVC pipe den using 3 inch PVC, my mantis's have grown to at least 5 inches and have gone through many successful molts.

The only fish i have been successful in keeping in the tank is the yellow tail damsels, i had 2, but one damsel killed the other. I also wanted to spice up my tank, but it wasnt until about a year or 2 after i got my mantis that i added coral. The problem you will face is you cannot keep a clean up crew with the mantis as it will kill all of it sooner or later. You would have to be doing regular water changes, especially while your tank is young, which isn't ideal. I feed my Mantis frozen shrimp 1-2x a week, and use tongs to "hand" feed it. They take some warming up, which is likely what you are experiencing, but once you get through it, you will see they are very inquisitive animals that you will catch watching you when you arent looking.

Feeding light will also help you keep nutrients down, Mantis Shrimps do not need regular feedings of several times a week. In fact, when I was feeding 3x a week, my Mantis actually started turning down food and being a lazy butthead in its den. It was not until i slowed down the feeding that it returned to its previous self.

I have managed to make a ton of mistakes in this hobby over the years, but my Mantis's have been able to survive all of it, so I have total faith in you.

Keep with the cycling and focusing on that, things will start getting easier and the Mantis will be more active before too long.

 

[wwarby]

Best of luck and way to go persevering. I've kept Peacock Mantis's for years, including when I was just restarting in the hobby. They are pretty resilient to water changes. Cycling the tank will help with keeping it stable, but the Mantis should be fine through the cycling process.

Ah thanks very much for the encouragement, much appreciated

I created a capital J PVC pipe den using 3 inch PVC, my mantis's have grown to at least 5 inches and have gone through many successful molts.

Mine is 2 inch PVC running all the way along the back of the tank with an entrance curved away from the straight section at each end, and a third entrance in the middle in a T junction. Oatmeal is at least 6-7 inches in length from eyes to tail I'd say, it's increasingly clear to me that she doesn't like the pipe diameter of her home as @nmotz predicted. For the last 24 hours she's been hammering the PVC entrance in a futile effort to make it bigger and moving rocks around but not actually covering her cave entrances except for one abandoned attempt. I may be wrong, but I'm interpreting her behaviour as wanting to molt but feeling it's dangerous or impossible in her inadequately proportioned home.

I've been thinking about what it might take to give her a bigger burrow. First and foremost it seems I'd need to temporarily evict Oatmeal into some kind of container full of tank water (a 5 gallon bucket?) so that I can safely manipulate the PVC and rockwork. It seems like the only way to catch her would be to lift out all the aquascaped rock (not easy because very big chunks of it are cemented together and would require breaking some epoxy bonds underwater without getting punched), and then to lift out the burrow with tongs, forcing her into clear water, then chasing her around with a couple of nets.

I figure I'd need to put the rock in big and deep containers of salt water to prevent all the bacteria I've spent weeks accumulating from dying off. Then I'd need to fabricate a bigger home for Oatmeal, put it back in the tank, put all the rocks back in position (possibly first hacking away at some of them with a hammer and chisel to accommodate the enlarged tubing underneath them, then reintroduce Oatmeal to the tank, working quickly enough to not lose temperature or oxygenation in the holding bucket in the meantime.

Meanwhile I need to actually find a supplier of 3 inch PVC tubing in the UK which is easier said than done, as it's not a standard size here - the standard sizes being 32, 40, 50 and 110mm (3 inches is about 76mm).

I'm dreading taking this on but at the same time but readying myself for having to do it because I can't just sit around watching Oatmeal's increasingly frantic efforts to do something only I can do for her.

The only fish i have been successful in keeping in the tank is the yellow tail damsels, i had 2, but one damsel killed the other. I also wanted to spice up my tank, but it wasnt until about a year or 2 after i got my mantis that i added coral. The problem you will face is you cannot keep a clean up crew with the mantis as it will kill all of it sooner or later. You would have to be doing regular water changes, especially while your tank is young, which isn't ideal. I feed my Mantis frozen shrimp 1-2x a week, and use tongs to "hand" feed it. They take some warming up, which is likely what you are experiencing, but once you get through it, you will see they are very inquisitive animals that you will catch watching you when you arent looking.

Interestingly the LFS staff in two different shops warned me off doing water changes in the first few weeks. I have actually done three or four so far anyway and I think it's about time that I started getting into a regular routine of 10% a week as that does seem to be the recommended pattern. I don't have a problem with doing this really - I have an RO unit so it's not much of a bother to mix up the water and change it at the weekend.

I also feed Oatmeal with tongs. She's veracious and swims up to the tongs like a bullet to snatch whatever is in them (she also makes a bee line to the same tongs when I'm using them to move rocks or debris). It's pretty cool when she does that. I have heard of some reefers having clean-up crew that get left alone, although I can't see Oatmeal being that neighbourly. I'll try a few snails and hermits at some point though just in case.

 

[wwarby]

@nmotz, I'd value your opinion especially on this. Do you think it would be acceptable to Oatmeal if I created a "chamber" of 3 inch diameter inside the mainly 2 inch burrow as shown in the drawing below?(the top version is the current setup, the bottom is the proposed new setup). The idea would be to use connectors that reduce/enlarge the pipe diameter like the ones pictured.

This would be somewhat less disruptive as I would probably not need to start smashing apart the rocks to make room for new burrow, but I'd much rather do the more disruptive change and replace the whole thing than try this first only to find it didn't help.

 

[Bhor217]

if the burrow is really the problem, you could place a temporary burrow in the tank and see if oatmeal will move to it. If it does, it will make your life easier with removing the rock under the aquascape. Another option would be to coax oatmeal into a net by forcing water through one side of its burrow and a net on the other side.

rock rubble is your friend, they love making "their own" burrow, mine constantly has rubble near their entrances, and even sometimes switches it up and hangs out in its "homemade" burrow made in the rocks.

The rubble will also get the shrimp out of its home and start moving the rocks, which brings its own entertainment, as they get their rocks jigsawed just right which is pretty cool to see.

They are HARDY animals, in fact, I came home from work one day and found my mantis had jumped my tank and was on the floor, picked it up with a net and put it back in the tank and it was like it never happened. Could have been on the floor for 5 hours for all I know!

 

[wwarby]

if the burrow is really the problem, you could place a temporary burrow in the tank and see if oatmeal will move to it. If it does, it will make your life easier with removing the rock under the aquascape. Another option would be to coax oatmeal into a net by forcing water through one side of its burrow and a net on the other side.

rock rubble is your friend, they love making "their own" burrow, mine constantly has rubble near their entrances, and even sometimes switches it up and hangs out in its "homemade" burrow made in the rocks.

The rubble will also get the shrimp out of its home and start moving the rocks, which brings its own entertainment, as they get their rocks jigsawed just right which is pretty cool to see.

The temporary burrow is a great idea actually, and one I hadn't considered. I think no matter what I'll do that over the weekend - if nothing else it will give me far more insight into whether the current burrow is actually a problem. I'll see if I can find some 3" pipe somewhere tomorrow and just lob it down the back of the tank for now.

I do actually have quite a bit of rock rubble in the tank and she's shown very little interest in it so far, although she does move pieces around occasionally. There might not be enough for her to make a full on cave, but there's also probably not enough room around the rocks in my aquascape for that either, and my sand bed is only about 2-3 inches deep so I don't really see much hope of her creating an effective cave of her own unless I add more sand and potentially redesign my aquascape. How much actual space does she need to create a cave of her own? The photo below shows the rock rubble in the tank, and the space constraints around the rock. I tried to offer a variety of differently sized rubble pieces but a lot of them are around 2" across and perhaps too big for the job? I used CaribSea LifeRock FragZone rocks and broke some of them up with a hammer and chisel. Maybe I just need more of the same? Or some small pieces of live rock rubble from the LFS?

They are HARDY animals, in fact, I came home from work one day and found my mantis had jumped my tank and was on the floor, picked it up with a net and put it back in the tank and it was like it never happened. Could have been on the floor for 5 hours for all I know!

That's crazy! I have a jump guard on my tank for that reason but it's impressive she survived that ordeal. Mind you, most people who get mantis shrimps seem to do it by accident inside live rock which has been transported out of water, so I guess it makes sense!

 

[Dinkins Aquatic Gardens]

Thanks - I’ll ask for a bottle of them next time I’m at the LFS. I do also have a big chunk of live rock in the display tank so if there were any copepods on that I might have a few in there by now, but I guess it can’t hurt to get more.

Definitely do! You literally can't have enough of these guys. They get into the crevices of your rock and eat detritus, feed your fish, feed your coral, etc. They are fantastic!

 

[nmotz]

@nmotz, I'd value your opinion especially on this. Do you think it would be acceptable to Oatmeal if I created a "chamber" of 3 inch diameter inside the mainly 2 inch burrow as shown in the drawing below?(the top version is the current setup, the bottom is the proposed new setup). The idea would be to use connectors that reduce/enlarge the pipe diameter like the ones pictured.

This would be somewhat less disruptive as I would probably not need to start smashing apart the rocks to make room for new burrow, but I'd much rather do the more disruptive change and replace the whole thing than try this first only to find it didn't help.

I can’t say if mantis shrimp are smart enough to find a wider space like that inside the pipe or not. If you want to keep him healthy long-term you will have to replace the pipe at some point or else he won’t be able to enter or exit at all. That’s one reason why I use a simple U-shaped pipe instead of one which has multiple tunnels. It’s much easier to upgrade. The other reason is because Peacocks build simple U-shaped burrows in the wild. IMO, a lot of people experience dissatisfaction with Peacocks because of burrow issues. Usually, no burrow is provided and the animal suffers too much stress to be interesting. That’s not the case with you of course, but generally speaking: the more suitable the burrow, the better it is for mantis shrimp health and behavior.

If you talk to people who have kept mantis shrimp of all types for many years, they’ll tell you hardiness varies widely. Based on numerous factors, it’s impossible to know exactly how reactive your specific mantis will be to water quality. That’s why I just use the guidelines posted by researchers such as Dr Roy Caldwell. He stated years ago in a post on Reefcentral that once he couldn’t keep nitrates below 10ppm he would start doing water changes or take other actions to reduce nutrients because it eventually leads to shell rot. Average nitrate load at the depth where Peacocks are most commonly found is about 2ppm.

For this reason I’d recommend work on your tank chemistry first then worry about the burrow.

 

[wwarby]

Thanks @nmotz, much appreciated. I'm very much still on the case with the water chemistry, but tested again today and things are still heading in the right direction with nitrites now down to about 0.025ppm - barely detectable on my test kit. Nitrates are still around 20ppm but my understanding is if nitrite has come down then nitrate will soon follow. Opinions do seem to vary greatly on how important the water chemistry is below a certain threshold but obviously I'll keep trying to get it lower. I feel like I ought to prioritise the burrow issue at the same time though - Oatmeal has been whacking the PVC for two days constantly now - she's clearly stressing about it.

Do you cap off one end of the U-shaped burrow? I've heard (can't remember it it was from you) that mantises don't really like burrows with multiple entrances so I feel like at minimum I should reduce the entrances from three to two, so discard everything right of the T junction. not sure though whether I should just cap off where the T junction is, leaving only one way in or out.

I'm thinking of going with 82mm outside diameter tubing which is 76mm on the internal diameter (exactly 3 inches). There are other sizes but I want to strike the right balance of making it big enough, but not so big she doesn't like it and not so big it's completely impossible to fit into my narrow tank and still have room around the aquascape to clean the glass. The only pipe sizes easily obtainable here in the UK are 32mm, 40mm and 110mm. Everything else is crazy hard to find and crazy expensive. Once I'm sure about the size and shape, I'll order the bits and do a trial run by placing a temporary new cave in the tank and see if she goes for it. If all is good then I'll take on the job of swapping it out permanently.

When you say that eventually she won't fit in the current burrow at all - are you saying she'll get even bigger than she already is? She's about 6-7" long already and I thought that was about as big as they get...

 

[Latte]

I'll do a bit of research on this as it's the first time I've heard the suggestion. I've no reason to think it's a bad idea, but $200 is not an insignificant amount of money to me so I'd want to be on pretty solid ground that I'm not just chucking money at a problem I don't currently have.


Yeah, this is a problem I've run into a lot. The LFS staff tell you to be wary of forum advice and the forum advisers tell you to be wary of the LFS staff. The YouTubers tell you to be wary of both, and everyone tells you to be wary of the YouTubers. LFS staff also tell you to be wary of advice from competing LFS staff . I've learned that advice differs wildly on many topics, so to the extent possible I try to absorb taking a broad sample of opinions and weight them based on perceived relevant experience and reputation to find consensus. For example a lot of people who have never owned a mantis shrimp (and some that have) will tell you they will kill everything in your tank, but there is plenty of hard evidence to the contrary.

My first LFS told me to fast cycle my tank with bottled bacteria with the mantis shrimp in it. They also sold me a UV steriliser (utterly unnecessary for my setup as far as I can tell), a cannister filter (widely considered the worst filtration mechanism for marine setups), a hopelessly inaccurate digital salinity meter instead of a refractometer and a test kit that has a poor reputation. I have cut ties with them and started using a local place which seems to be widely reputed to be one of the best in the country (Advanced Aquarium Consultancy in Harlow). They seem much less interested in selling my random stuff I don't need, and so far the advice they've given me has borne out as accurate. I'll always need to balance what they're telling me against competing opinions and especially where mantis shrimps are concerned I value the advice on forums from people who have actually kept them more than the LFS, but I definitely want to keep them included as part of my information diet for now.


Yeah, I'm definitely worried about her first molt. @nmotz thinks the burrow I've built is too narrow because she won't be able to jack-knife inside it whilst molting, and he may well be right. Her behaviour makes me think she wants the burrow to be bigger - she regularly hits the inside of it and occasionally seems to try to make a different burrow (which is impossible with my aquascape). Fixing it now though would be very difficult, requiring all the rock to be removed and reshaped around a bigger burrow and I suspect I'd be more likely to kill her or crash the tank by doing that than hoping she can molt in the existing burrow.


This does make sense and I need to take it seriously. The point of the tank is to have a mantis shrimp in it - fish are a side show for when the main star (Oatmeal) is in her dressing room. If I overfeed Oatmeal as a tactic to keep the fish alive and she becomes more reclusive as a result I've done myself no favours whatsoever. Perhaps I should just take my chances, keep the feeding at current levels and hope she just doesn't bother the faster fish.

Anyway, I'm gonna hold steady for the next few days or weeks, watch to see if she looks like she's gonna molt, keep tracking my levels and only when I'm sure it's the right time, then I'll try a couple of fish and cross my fingers for them.

For what it's worth, there's definitely plenty of bad advice on the forums, on YouTube and from LFS. At least on reef2reef, you usually get a bit of a consensus. I wouldn't trust what just one person says, but when multiple people chime in and agree you're likely to be safer trusting that idea.

Generally I think YouTube has a lot of great advice though. BRS especially on YouTube is an incredible resource for all things reefing, though definitely focused more towards corals.

 

[wwarby]

For what it's worth, there's definitely plenty of bad advice on the forums, on YouTube and from LFS. At least on reef2reef, you usually get a bit of a consensus. I wouldn't trust what just one person says, but when multiple people chime in and agree you're likely to be safer trusting that idea.

Generally I think YouTube has a lot of great advice though. BRS especially on YouTube is an incredible resource for all things reefing, though definitely focused more towards corals.

Yeah, you don't want to know how many hours of BRS TV I've watched

That is generally what I'm doing though - looking for consensus and reef2reef has been an invaluable and trusted source of information for me, and I'm really grateful to the community for helping me as I'm getting started.

 

[wwarby]

I've ordered some 3 inch PVC. Two 90 degree bends, one 45 degree bend and about 3 ft of tube. Total cost £62 (over $70) - unbelievably expensive for a few bits of moulded plastic but this needs to get done sooner rather than later - aside from anything else Oatmeal is driving me mad by hammering on her burrow all the live long day

She's been shuffling rock rubble around all day today, arranging it in piles in front of her burrow. Not sure if she's gonna try to molt before I can get the new PVC in there as it won't arrive for another two or three days, but if it does arrive before she's closed the burrow I'll try to give her a better home to do it in.

I've made a homemade trap from a big water bottle with the lid cut off and inverted - I figure it might be a less difficult job overall if I can catch Oatmeal first and remove her, so that I don't have to lift all the rocks out of the tank to make the changes. I figure I'll put a prawn in the trap and as soon as she enters it I'll cover the front with a net and lift her out into a waiting bucket of tank water, then immediately set about replacing the burrow. I assume she'll be safe in a 5 gallon bucket for a few hours? I'll make a mesh lid so she has air and light. If there any danger in using the trap mechanism I've described?

 

[Tired]

That's how people catch mantis shrimp normally. A 5-gallon bucket is absolutely fine for a few hours, though a pump or airstone would be a good idea. Preferably, give her a chunk of something to hide in while she's in there. No need for light, just for some amount of air circulation and for her to not be able to jump out.