BogMonster's Red Claw Crab Adventures

BogMonster
  • #1
I'm setting up a terrarium for a Red Claw Crab. Nowhere else I've seen has any care information beyond a basic sheet, outside of this forum! So I thought I could maybe both get some guidance and add to the pool of information, by recording the progression of this tank in this thread.

So I've got a 12w x 18l x 12h terrarium. Substrate includes sand and lava rock. I used plastic egg crate, zip ties, and organic landscaping fabric to create a land shelf without losing my aquatic space. I've also got a mechanism set up to connect a separate dig box in which I plan to use a mixture of potting soil, coco coir, and sphagnum moss and which will have its own heat source. I'm still deciding which section to put the UV lighting on, or if I should invest in a second UV light.

Plants currently include Lucky bamboo, as I had some sitting around and it's one of the toughest plants I've met that can stand being directly in water. I read that Red Claws destroy plants a lot, and I figured they would have to work a little harder to ruin this, if it can acclimate to the salt. Nothing else yet, as I wanted to make sure I could get the tank running first. There's also a cork bark flat to bridge from the water to the land, and a piece of driftwood. I read that Red Claws like a salt level of 1.005 so that's what I'm shooting for, using Instant Ocean sea salt.

Filter is a strange tiny cannister filter I got from a LFS. The name of it escapes me right now but it's the only thing I've been able to find available near me that will function in about 5" of water. The filter is driven by an air pump. Inside it I've placed ceramic media, filter carbon, and bio sponge.


20230727_150146.jpg

As of right now, there's no critters in this tank. I've been adding a few fish flakes a day to try to get the bacteria cycle started. It's slow going.

The issue I'm running into currently has to do with the filtration and the bacteria cycle. It's finally starting to convert the ammonia a little, but it's stalling at nitrite and only barely starting to go to nitrate. I've been adding some QuickStart and waiting, hoping that it will finish cycling soon. Is there anything else I can do besides add bacteria and wait?

Secondly, after running for a few weeks, this tank smells! Really bad! I got it to calm down some by getting a higher-powered air pump, but if I touch the water or move anything, it fills the room and lingers on my skin. Is my filtration not doing enough, or does brackish just smell awful for some reason anyway? I really feel like this isn't supposed to happen but I'm not sure what to do about it. Do I need to pull the tank down and try again?

Today's water quality test had PH at 7.8, while my other tanks run 7.6.


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20230727_144745.jpg
 

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Fishfur
  • #2
I'm setting up a terrarium for a Red Claw Crab. Nowhere else I've seen has any care information beyond a basic sheet, outside of this forum! So I thought I could maybe both get some guidance and add to the pool of information, by recording the progression of this tank in this thread.

So I've got a 12w x 18l x 12h terrarium. Substrate includes sand and lava rock. I used plastic egg crate, zip ties, and organic landscaping fabric to create a land shelf without losing my aquatic space. I've also got a mechanism set up to connect a separate dig box in which I plan to use a mixture of potting soil, coco coir, and sphagnum moss and which will have its own heat source. I'm still deciding which section to put the UV lighting on, or if I should invest in a second UV light.

Plants currently include Lucky bamboo, as I had some sitting around and it's one of the toughest plants I've met that can stand being directly in water. I read that Red Claws destroy plants a lot, and I figured they would have to work a little harder to ruin this, if it can acclimate to the salt. Nothing else yet, as I wanted to make sure I could get the tank running first. There's also a cork bark flat to bridge from the water to the land, and a piece of driftwood. I read that Red Claws like a salt level of 1.005 so that's what I'm shooting for, using Instant Ocean sea salt.

Filter is a strange tiny cannister filter I got from a LFS. The name of it escapes me right now but it's the only thing I've been able to find available near me that will function in about 5" of water. The filter is driven by an air pump. Inside it I've placed ceramic media, filter carbon, and bio sponge.

View attachment 885660

As of right now, there's no critters in this tank. I've been adding a few fish flakes a day to try to get the bacteria cycle started. It's slow going.

The issue I'm running into currently has to do with the filtration and the bacteria cycle. It's finally starting to convert the ammonia a little, but it's stalling at nitrite and only barely starting to go to nitrate. I've been adding some QuickStart and waiting, hoping that it will finish cycling soon. Is there anything else I can do besides add bacteria and wait?

Secondly, after running for a few weeks, this tank smells! Really bad! I got it to calm down some by getting a higher-powered air pump, but if I touch the water or move anything, it fills the room and lingers on my skin. Is my filtration not doing enough, or does brackish just smell awful for some reason anyway? I really feel like this isn't supposed to happen but I'm not sure what to do about it. Do I need to pull the tank down and try again?

Today's water quality test had PH at 7.8, while my other tanks run 7.6.

View attachment 885661View attachment 885663View attachment 885662
Brackish should not smell awful but if it’s not getting enough circulation that can cause odour issues. Are there any leaves or is the soil full of organic matter? Either could be the source of the stench.

If you can scoop up a bit of the soil, and it smells worse than the water does, that’ll be a clue.
 

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BPSabelhaus
  • #3
Well, the luck will run out on that bamboo.

Mangrove trees OTOH do great. Mine are currently in the garage as I transition my tank from brackish to full salt (always ran between anyway) with no fish. Just crabs, snails pile worms and trying anemones. When I had two crabs all was well. But these new ones are escape artists and so have a screen for now. Need to trim out space for the trees, and I’m feeling lazy.


IMG_1022.jpeg

Filter is a simple sponge filter. There are clams, mussels, barnacles etc… here and there as well.
 

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Fishfur
  • #4
Well, the luck will run out on that bamboo.

Mangrove trees OTOH do great. Mine are currently in the garage as I transition my tank from brackish to full salt (always ran between anyway) with no fish. Just crabs, snails pile worms and trying anemones. When I had two crabs all was well. But these new ones are escape artists and so have a screen for now. Need to trim out space for the trees, and I’m feeling lazy.

View attachment 885689

Filter is a simple sponge filter. There are clams, mussels, barnacles etc… here and there as well.
What species is that conical snail? Just curious. Looks like a very interesting project.
 
BPSabelhaus
  • #5
What species is that conical snail? Just curious. Looks like a very interesting project.
Black devil spike var. Capuccino

Came with a tank I inherited. Discovered they actually prefer salt / brackish so I acclimated them to that tank.
 
Fishfur
  • #6
Black devil spike var. Capuccino

Came with a tank I inherited. Discovered they actually prefer salt / brackish so I acclimated them to that tank.
I wondered if it was Faunus ater - aka Cappuccino. I have had a few of them too, but in freshwater. Does not surprise me they prefer brackish but they seemed ok in freshwater.
 

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BogMonster
  • Thread Starter
  • #7
Brackish should not smell awful but if it’s not getting enough circulation that can cause odour issues. Are there any leaves or is the soil full of organic matter? Either could be the source of the stench.

If you can scoop up a bit of the soil, and it smells worse than the water does, that’ll be a clue.
Substrate is just play sand and lava rock from the landscaping department at Lowe's; I washed it before using. I also have this as substrate in another tank whose only issue is that I added Rabbit snails without realizing how much waste they make, and the crappy stock filter can't keep up now.

No leaves but maybe the driftwood could cause that? I thought I soaked and boiled and baked it enough, but maybe not... There shouldn't be any other organic matter besides fish flakes and lucky bamboo.

The water smells bad, the substrate smells worse. The filter smells atrocious.

I did finally locate the name of the filter! It's a Lee's Triple Flow corner filter. (Cat. no. 13405). I was going to use something more like the Tetra ReptoFilter but I couldn't get my hands on one.

Today's test results:
PH 7.6
Ammonia 0.5ppm
Nitrite 5.0ppm
Nitrate 10ppm

So we're getting closer to full conversion! It still smells bad though.
Update: Upon further examination of the back sides of the tank, I may have something growing in the substrate that shouldn't be there? The black stuff is what I mean. The red is dust off the lava rock, but I didn't put anything black in this tank.


20230728_120510.jpg
I'm doing some more reading on this and I found a thread on a reef forum discussing hydrogen sulfide that had pictures similar to what I'm seeing in my tank. The resource they linked to explain how it gets there etc details that the combination of uneaten fish food and low oxygenation creates the perfect environment for a certain type of bacteria to grow. If I'm understanding this right, the bacteria metabolize the sulfites in the fish food into hydrogen sulfide and can release it into the water column, where it will be toxic to fish.

So it's sounding like I need to pull this tank down and try again with a different filter and another airstone?
 
BogMonster
  • Thread Starter
  • #8
So, I have a 12w x 18l terrarium with a water feature of around 8 gallons. I'm planning to put a Red claw crab in it, but I want to make sure I have the setup working first. It's brackish to a salinity of 1.005 and still establishing a nitrogen cycle. There are currently no live creatures in this tank! I've just been adding fish flakes a little every day to try to establish the bacteria cycle. Substrate is sand and lava rock.

This tank smells. Bad. The water smells, the substrate smells worse, the filter smells atrocious. And today I discovered this black stuff growing in the sand on the back side of the tank:


20230728_120510.jpg

Is this hydrogen sulfide? If I get a more powerful filter and move the air pump to a bubble tube, will it go away? Or do I need to take this tank all the way down and try again?
 
Fishfur
  • #9
Substrate is just play sand and lava rock from the landscaping department at Lowe's; I washed it before using. I also have this as substrate in another tank whose only issue is that I added Rabbit snails without realizing how much waste they make, and the crappy stock filter can't keep up now.

No leaves but maybe the driftwood could cause that? I thought I soaked and boiled and baked it enough, but maybe not... There shouldn't be any other organic matter besides fish flakes and lucky bamboo.

The water smells bad, the substrate smells worse. The filter smells atrocious.

I did finally locate the name of the filter! It's a Lee's Triple Flow corner filter. (Cat. no. 13405). I was going to use something more like the Tetra ReptoFilter but I couldn't get my hands on one.

Today's test results:
PH 7.6
Ammonia 0.5ppm
Nitrite 5.0ppm
Nitrate 10ppm

So we're getting closer to full conversion! It still smells bad though.
Update: Upon further examination of the back sides of the tank, I may have something growing in the substrate that shouldn't be there? The black stuff is what I mean. The red is dust off the lava rock, but I didn't put anything black in this tank.

View attachment 885752

I'm doing some more reading on this and I found a thread on a reef forum discussing hydrogen sulfide that had pictures similar to what I'm seeing in my tank. The resource they linked to explain how it gets there etc details that the combination of uneaten fish food and low oxygenation creates the perfect environment for a certain type of bacteria to grow. If I'm understanding this right, the bacteria metabolize the sulfites in the fish food into hydrogen sulfide and can release it into the water column, where it will be toxic to fish.

So it's sounding like I need to pull this tank down and try again with a different filter and another airstone?
Hydrogen sulfide is a gas produced by anaerobic bacteria - aka swamp gas among many other names. If you’ve got a patch of substrate that’s been oxygen deprived, the bacteria in it could easily be producing the gas and the stench.

Small blackened spots under a layer of something like sand can indicate the presence of the causative bacteria.

To avoid having this happen again, you need a coarser substrate so some oxygen gets to all areas and probably better current in the water. If the sand is relatively shallow, MTS snails might be useful to help keep it turned over and somewhat aerated but they don’t burrow all that deep - I think not more than an inch or maybe an inch and a half.
 
BogMonster
  • Thread Starter
  • #10
Hydrogen sulfide is a gas produced by anaerobic bacteria - aka swamp gas among many other names. If you’ve got a patch of substrate that’s been oxygen deprived, the bacteria in it could easily be producing the gas and the stench.

Small blackened spots under a layer of something like sand can indicate the presence of the causative bacteria.

To avoid having this happen again, you need a coarser substrate so some oxygen gets to all areas and probably better current in the water. If the sand is relatively shallow, MTS snails might be useful to help keep it turned over and somewhat aerated but they don’t burrow all that deep - I think not more than an inch or maybe an inch and a half.
Coarser substrate in what way? The whole point of the sand was that Red Claws like to burrow in it, from what I've read. It's also interspersed with lava rock gravel ranging in size from 0.5 inch to about 2 inch. I'm not sure how I could get much coarser than that while still allowing the crabs the natural opportunity to burrow?

I've pulled the tank down for now while I figure out what to do differently, but I really do want to understand.

I'm looking into different filters because what I was reading said water flow can play a big role in that, and admittedly the little corner filter was not making much current at all. I could get a bubble tube to line the long wall of the tank instead of just the one air stone powering the filter.

I really feel like the crab could do with a lower water level, but I'm having trouble finding a filter that would work with that. I heard the 20G ReptoFilter can operate around 2-3" of water but I spent two weeks going around to different pet stores trying to find one and nobody had one. They had the filter cartidges, but no one stocked the actual filter. I tried to order online and they said it was shipped but it never arrived. That was weeks ago. So I just don't know what to do for a filter that wouldn't require spending a few hundred dollars on a larger tank and the bits and pieces to go with.
 
Fishfur
  • #11
Those little corner filters were extremely popular when I first got into fish, way back in the distant past. There’s a filter made by Cobalt that works in very shallow water - the Clear Vue. I have some and they’re quite good - but the water output is at the top and makes for a little waterfall and not much current. There are 3 sizes. They come with a filter sponge stuffed in the bottle but you can reduce the sponge and add some ceramic if you like, even a bit of floss if you want.

Clearvue Mini Internal Filter

By coarser, what I meant was a sand with with larger and irregular grains. Coarse horticultural sand or possibly sand for making concrete. Any gravelly bits in sand always end up on top and the very finest particles always end up at the bottom

It’s just the way gravity and particles like sand and gravel function. Unfortunately it means that adding gravelly bits to sand does not make it coarser.
 

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