Missing hermie and flies

[Mom's got crabs]

Backstory and info: I got my crabs in August from a friend. I then recently (1 month ago) bought 2 more so 4 in total ranging from small to one fairly big guy. I use sand and eco earth coco fiber substrate 6 inches deep. I have both fresh and salt water (declorinated) dishes in my 20 gallon tank. Hooded light, gauges 80 f, 85 humidity , mister. Feed them hermit meal and a variety of nuts, and spinach sometimes.
I think that's all the vital information needed.
Anyhow,
I'm very concerned because one of my newer crabs is missing. I'm pretty sure he didn't get out of the tank, but I have no clue where he went. He's the small to medium sized one, and recently changed shells. I have read and researched as much as possible so I know it's possible he's molting (and that some can molt upto a couple of months at a time) but I'm worried and have been trying to look for him without being disruptive to him. I've picked up all the shelters and bowls just to see and I swear I have looked everywhere except for digging through the very center of the tank.
NOW, I just recently realized I have a bug infestation, and I'm starting to worry that he's dead somewhere and that's why the bugs are there. The bugs don't appear to be causing harm to my other guys, there's a few present outside of my tank- I also just brought in my very large monstera plant from outside for the winter and put it next to the tank, so that's another variable that I've read could cause bugs( though the bug presence is not significanton the plant- just a few flying around when I open the tank). I'm at a loss and I don't know if I should go digging more for a dead crab or trust that he's fine and molting.
Also, their tank setup is new so I'm wondering if I over wet the moss that I added when I did, and it brought some type of mold. There is no distinctive bad smell.
- I set up the new tank and habitat when I bought the 2 new guys and I iso'd them and gradually introduced everyone safely and everyone has adjusted well. They all seem to get along- I was very worried because when I bought the two new ones they were huge compared to the little guys I already had. But everyone is all good now.
*the bugs are a type of fly, I thought fruit fly at first but I've been horrified by reading into the bug forums on here so now I realize it could be a few different things.
They are very small and black/Grey and somewhat resemble the fruit fly.
Also to add, it's probably been a week since I've seen him.
I think that's everything.
Thanks for reading! Please help this new crab mom

[Brian_T]

In all likelihood the crab is molting or otherwise de-stressing under the substrate. It's nerve-wracking at first, but you get used to it.

Are the bugs generally hovering around or do the they spend most of the time running on surfaces, even when startled?

There probably fungus gnats. Not harmful, just annoying.

Humpback flies would be a bigger issue. They do fly but prefer to run away and are hesitant to fly. Fungus gnats do run on surfaces, but will usually fly if startled.

There is a "what is that bug" thread with more details.

Best to try to catch one and try to look at them under magnification. Maybe get a picture if you can.

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[Mom's got crabs]

Ok thanks. I'm just stumped because I have no idea where he could be. Usually they're (the crabs) easy to spot, like under a water dish or whatever.
The flies hover and fly alot. But they also appear to settle into things and if I move something they appear, flying again, if that makes sense.
They like the moss for sure, I actually discarded a bunch of it last night because I was concerned that was the culprit but I don't think so now. I did try to get a picture but they're so tiny and fast moving, it makes it difficult. I'll try to catch one and post. Thanks!

[Brian_T]

OK, that does sound like fungus gnats. I had an invasion last year when I brought plants in for the winter. They do hang out in the moss. I managed them by cleaning out moss regularly. You can eliminate them, by getting beneficial nematodes.

Crabs disappearing for a while is part of game. It's not unheard of for their molting cycles to occasionally line up. Around here that is called having "pet sand".

It's always little thrill when a crab re-emerges looking fresh and new.

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[Mom's got crabs]

Ok well that all makes me feel better! Should I move my plant and or treat it at all?
Do the nematodes just go away after you put them in and their job is done? I just looked up what it was and it kinda freaks me out but says it's safe for humans and pets.
Also, lol, what does pet sand mean exactly?- because they're hiding in it?

[curlysister]

Try not to worry. Crabs will dig to de-stress, to molt, or just for fun. They will back fill their tunnels so you won't know where they are. They can disappear for days or weeks or even months at a time. Don't start to worry until at least four months. And even then, there are few times that you should dig up crabs. A bacterial bloom, a flood, or if you need to move homes are some of the few situations in which it is advisable to dig up your crabs.

Most bugs that occur in a tank are not harmful to the crabs. Are you able to post a photo of the bugs?

[Mom's got crabs]

I tried to get a pic but they're so tiny and fast I haven't been able to but I'm pretty sure they're fungus gnats now, they seem to love the moss. I think I need to replace the moss but one of my crabs really likes hiding in it and I don't want to disturb him. Also, if I replace it right away, it's just a new place for the gnats right?

[Mom's got crabs]

UPDATE
so I got the fly issue under control, they were gone for a few weeks, so it seemed. My missing crab is still missing (Gary). Then Nemo (one of my smaller guys), went down for molting maybe a week ago. I figured he was following suit. Well the flies came back with a vengeance about a week ago and today it's even worse. I have double sided sticky traps on the out side of the tank and on the underside of the hood. It's catching them but there's soooo many that it is not enough. I moved all my plants away from the tank. I removed the moss I had, and I recently stopped providing fresh food, so I'm only using the ground fish meal. The bugs are dying in the water dishes, and my two other crabs have been super inactive.
I'm worried the fungus gnats are a sign that Gary has died. I'm at such a loss as to what to do.
I'm also getting a much larger tank which I will set up and move the two guys that are still out and about in the tank, in hopes of having a fly free home for them.[/img]
My question... in the meantime, can I change the top layer of my substrate without disturbing any molters because I think that's part of the problem?
Aside from that I know it's not recommended to go digging around for Gary but this bug issue is so horrid, I can't deal with them, they gross me out so bad that it makes it difficult to change the water and food out.
Also, there is no distinctive smell of anything dead but if he's deep enough maybe there wouldn't be a smell if he were dead?
I do not know how to attach a picture of the flies.

[myllkti]

I would think that it would be risky t o remove the top layer, since you don’t know how deep the sub is and may expose him if you remove too much, especially since you plan on moving them. So my guess is that it would be best to just wait till the move itself

[Mom's got crabs]

Thanks for replying! I was just about to make a new post because I didn't think anyone would see this.
Anyway, yeah I agree that it could be risky but the bugs are really becoming a nuisance and I'm worried that they are bothering my 2 guys that are still out and about.. their activity lately is very low, I haven't even seen my littlest guy (Little Tim), who is the most active lately.
I did some reading last night and am now concerned that I have a possible flooding or over moisture issue especially because I smell a light moldy smell from the tank. And now I'm wondering if it's a bacterial bloom since there are so many bugs... I read that is dangerous for the crabs. But I don't know what to do since two crabs are molting (hopefully). And when I get the new tank, I still have to wait for the mting guys to come up right?
I seriously can't deal with these bugs. I guess I have a bit of a bug phobia- I'm terrified of spiders.. every time I open The tank, I feel like the bugs are crawling all over me and I become super itching (they aren't actually all over me, maybe one or two actually exit the tank when I do open it) but it's causing me alot of stress and it's hard to want to change the food and water , although I obviously have to suck it up and do it.
Is there anything I can do to help the moisture issue or fix the possible bacteria bloom?

[JoeHermits]

A bacterial bloom would result from a lack of oxygen in the substrate, which is not beneficial for insects.

How moist is your substrate? Letting the top inch or so of sand dry out helps with fungus gnats, otherwise add a shallow layer of pure sand (fungus gnats can’t lay eggs if there’s no organic soil).


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[Mom's got crabs]

A bacterial bloom would result from a lack of oxygen in the substrate, which is not beneficial for insects.

How moist is your substrate? Letting the top inch or so of sand dry out helps with fungus gnats, otherwise add a shallow layer of pure sand (fungus gnats can’t lay eggs if there’s no organic soil).



Oh okay.. I was under the impression that when you have a bacteria bloom that fungus gnats show up. I must have misread. So I have coco fiber sub mostly on the top and sand on the bottom. I got worried that maybe my sand is too wet. I also made the mistake of putting aqua balls on one side of the bottom because I was going to try and make a natural pool with it at first and then it didn't work out (newb stuff lol). I'll try n figure out how to get a picture. So layer dry sand on top?

[Mom's got crabs]

https://imageshack.com/my/images

Figured it out!
Please excuse the dirty tank, I need to clean it but haven't been wanting to disturb the crabs (and the bugs lol)

[Mom's got crabs]

In the first picture, you can see the sand. The top layer appears to be much wetter than the under layer.

[JoeHermits]

The link isn’t taking me to your image, but a layer of pure coconut fiber is perfect for fungus gnats. No wonder they’re so bad!

A thin layer of sand on top will keep out the adults. The larvae already in will still emerge, so you won’t see results right away, but they won’t be able to lay their eggs. Combine that with your traps and hopefully your insect infestation will go away within a few weeks.


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