HCA: Hermit Crab Association

Hello! I was wondering if someone could describe to me in depth what a bacterial bloom would look like? My substrate looks okay I think but I’m not really sure, it’s all eco earth and it’s not too wet at all but there’s small patches of what I think might just be from humidity or condensation but it’s sorta white? Maybe it’s also from spilled salt water I’m not really sure. Two of my crabs have been underground for a little over a month now and I’m beginning to get worried. Another just went under a day or two ago and I have a single crab on the surface alone now ): I was just hoping that I didn’t get a bacterial bloom or anything in my substrate that maybe killed my two crabbies underground? Or maybe they’re just taking forever to molt? I’m very paranoid about one of my crabs dying and right now I’m just stuck! Any help or advice would be greatly appreciated! I’ve had the two who went underground for almost a year now, and I got the other two a few months ago from my friend who got them at the same time as I got mine.

Molting can take weeks to a few months, so I wouldn't be worried. I had a small bacteria bloom that was blue/greenish and smelled VERY rotten so I wouldn't be concerned by the white you are seeing.

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I had all sand at the time so I can't offer you any concrete advice. Is there any chance it's just mold? If so it's no biggie to the crabs.

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It’s white and maybe the very very slightest tinge of green. But barely, my eyes might be tricking me and my tank smells like it normally does. Nothing rotten or anything just the eco earth. I think the white I’m seeing is just trapped humidity over time, and algae forming maybe. I might just be over thinking it. One of the two that is under molted earlier this year for a fact but the second has had their fair share of being underground for a long time. I think if there was a bacterial bloom I’d definitely know for sure with no doubt about it... but still I have my worries. I’ll have to post a picture sometime during the day.

With having just EE as substrate you run a higher chance of getting a bacterial bloom. Since EE is only ground up coconut husk it can rot quicker than a mix with playsand. There is a good chance the white you are seeing is just from food the crabs drug off if it is on the surface too. If it's just on the surface scoop it out.

Without pictures it is hard to tell what exactly you are dealing with. I would check the following things first.

Is you substrate extremely wet the deeper you go? This quick check works with playsand and EE mix. Not sure how well it will work with just EE. Slide a butter knife down the front of the glass and wiggle it to form a small pocket. In a few minutes water may pool in the hole. If the water pools you have a flood.

The only real way to tell for sure is to scoop one area out all the way to the bottom. A bloom will reek. It can smell like different things, rotten eggs, ammonia, moth balls and more.

I did the test and there was no flooding! I don’t mist my tank too often because it retains humidity well. There was no stink and the “white” I was seeing completely disappeared in the spot I stuck a fork end into, so my guess is maybe it’s gathered humidity in the substrate.

You can check the crabitat conditions section for my latest thread and recent bacterial blooms if you'd like. I would get a spoon and dig down in a corner where the crabs aren't. Just one scoop at a time until you get completely to the bottom. Smell each scoop of sub. If you get to the bottom and smells no different you will have eased your mind at least. When I did this, the smell change was not that noticeable... when I removed all of the sub it smelled terrible with the entire room smelling like sulfur and rotten eggs.

I posted a picture that was what got me to that point. There was a dark green line in my sub you can see if you do read through my post. There is good info in there from others as well. After I changed all the sub and cleaned everything, I decided to check the 10 gallon where the crabs were temporarily held until I cleaned the first tank. The 10 gallon showed zero signs of a bacterial bloom (just looking at it was fine/normal looking) and both tanks held shape with a straw and no flooding, but I believe they were just too moist even without flooding or any pooling of water.

I redid the tank with 50/50 playsand to EE mixed well... just kept mixing to get as even as I could. I also had a 3rd small tank that was just as moist for just as long as the other two (about 5 gallon or so), but with only EE as the substrate. After all of this, I of course dumped all of that EE as well. Thing is, that tank showed no signs and did not smell at all so was probably unnecessary, but was doing all the tanks so did that one again too.

Just wanted to point out that with the spoon at the bottom, it really didn't smell too bad... just... different from good to bad. Again, when I removed it all it smelled atrocious and so much stronger at the bottom. Also, the 10 gallon substrate looked perfectly fine with a full on bacterial bloom so please check and smell to the bottom. Both tanks smelled perfectly fine if I stuck my nose in lol. That would be my advice though; to dig and smell.

Good luck with everything and I hope your crabitat is fine! Keep us posted.