What killed all my hermit crabs?

[HomerJ]

Hi all:

I started finding dead hermit crabs in my tank about 10 days ago.  The shells were not picked clean, the crabs were still in there, just dead.  They then all died, one after the other.  I think I got the last shell last night.  That's about 20 crabs, in a week!  These crabs had been in my tank for 4 months and I had no die off before that.

Crabs had plenty of different size shells to move into, and the tank is relatively clean, but there was plenty on the rocks for them to munch on.  The fish (2 clowns) appear happy, and so is the cleaner shrimp.  Corals (Torches, Frogspawn, GSP and Xenia) are all happy and fully extended.  Snails appear healthy too (i.e. I haven't found dead ones in a while).

The fact the shells have not been picked clean lends me to believe it is not a predator.

I also have not done anything to the tank in a while, aside from "fragging" a few Xenia heads.

Checked my water again last night, and :

Ammonia  0
Nitrites 0
Nitrates ~0 (barely registers)
Copper   0
pH       7.8 or 8.0 (depending whether I trust my test kit, or my impossible to calibrate digital Aquatics pH probe)
Ca2+     340  (This is pretty low, I need to crank it up a bit)
dKh      8 (143ppm) (Again, pretty low).


Does anything come to mind?  I will need to get new crabs before the tank looks like the bathroom in a Taco Bell, but I'd like to know if something is before sending another bunch of crabs to their death.

Thanks for your help.

[NanoSF]

I have given up on hermits, snails are so much more important. I would just get some more snails instead. I find hermits die for no reason too. If you are not worried about your rockscape or corals getting knocked over get a Mexican Turbo snail. They are just beasts.

[rush]

I would definitely still keep hermits, snails are good yes but still need some hermits. I have no clue what could have happened to them, sounds like they were poisoned but by what I have no clue. That is strange indeed, hermits normally troop through anything. Your water parameters are fine, so I don't really know what happened to them .

[redbelly]

Have you added anything to your system recently?

Copper is the first thing I would look at in your shoes.

[rush]

Have you added anything to your system recently?

Copper is the first thing I would look at in your shoes.

That's what I thought as well, but he said his copper is 0.

[redbelly]

I would check again with another test kit. Copper can be tricky to test for.
And I would do some serious water changes and run carbon just the same to be sure.
If its a a water quality issue this will also help address this issue.

[HomerJ]

Have you added anything to your system recently?

Copper is the first thing I would look at in your shoes.

Nope, nothing added to my system.  Copper?  In my shoes?  But I keep fish in the tank, not my shoes! ;-b  Sorry couldn't resist!

I'll invest in a better test kit and see.  But wouldn't snails go kaput too if it was copper?

Thanks for all the replies.

[redbelly]

lol, yeah i meant if I were in your shoes 

Copper can be a strange thing in low doses. Some inverts can be effected while others are not.

Personally I would see if you can use someone elses kit.
Instead of buying another test kit just buy some good carbon and some good water changes. IF its in the system you are going to have to do this anyways so skip the extra cost of another test kit imo.

[HomerJ]

lol, yeah i meant if I were in your shoes 

Copper can be a strange thing in low doses. Some inverts can be effected while others are not.

Personally I would see if you can use someone elses kit.
Instead of buying another test kit just buy some good carbon and some good water changes. IF its in the system you are going to have to do this anyways so skip the extra cost of another test kit imo.

I'm already running carbon/phosban in a TLF reactor.  As for water changes, this weekend is perfect timing, as I was going to swap my sump for a different one that will accommodate a bigger skimmer.  For this reason, I prepped 20 gallons instead of the 10 gallons I normally change since I knew I'd be emptying the sump anyway.

Thanks for your reply!

[bandit]

quick q do you have a pistol shrimp, I had one that would snap at my hermits, kill them then toss them out of his burrow.

[HomerJ]

quick q do you have a pistol shrimp, I had one that would snap at my hermits, kill them then toss them out of his burrow.

No, not that I know of anyway.  2 clowns and a cleaner shrimp.  I think I got all the hitchhiker crabs too.

[HomerJ]

Grr.  Added 5 crabs about a week ago... They all died again. 

I spent enough time with the red flashlight at night that I'm 99.9% sure it's not a predator.  Aside from copper, what else could cause this?  Snails, shrimps and fish look happy...

[NanoSF]

I still say go without them then. They kill each other, they die unexpectedly (often without explainable reason), and they far less important than snails. I have no help for you in explaining their deaths, but I think you would be far less stressed out about what is going on if you just stayed away from them. There is nothing a hermit does that a mixture of different snails couldn't do just as well if not better.

My only guess if it was 7 days would be acclimation problems, but I can't see your tanks being that far off the LFS. Also, I don't think a lack of iodine could kill them this fast but do you dose iodine? Maybe it would help.

[bandit]

curious have you ever checked your hydrometer to see if its accurate. I had one that was actually 1.030 when it displayed 1.024? Your livestock would get used to it over time but new hermits would not make it.

[Darth]

curious have you ever checked your hydrometer to see if its accurate. I had one that was actually 1.030 when it displayed 1.024? Your livestock would get used to it over time but new hermits would not make it.

thats why I use a refractometer

[HomerJ]

I use a refractometer too, and use calibration solution every month to adjust it, so I doubt salinity is an issue, unless my calibration solution is bad of course.

[Tsukiyomi-sakura]

Where are you buying your hermits from? That could potentially be part of the problem if your not getting them healthy in the first place.

It does sound like copper or PH but your PH is fine.

What type of hermits? maybe they are killing eachother? but it is possible the fish are also doing it, or stressing them out to a point where they die.

[redbelly]

Do you use ro/di water to calibrate your refract?
or a salinity solution?
ro/di does not work for calibrating refracts.

As for hermits not being the best, I am really not sure that I agree with this. Some hermits are certainly better than others. Some are more aggressive and some are less. imo the bext hermits are scarlets. I do also really like the electric blue legs (not to be confised with the standard blue legs of course)

Yeah its quite strange that you are loosing hermits like that.

[HomerJ]

Where are you buying your hermits from? That could potentially be part of the problem if your not getting them healthy in the first place.

I don't think it would be fair to name the shops here, without knowing that they are part of the problem.  I can say I have bought the same type of crabs from 2 different places with same results.

It does sound like copper or PH but your PH is fine.

Well I'll need to find someone with a good copper test kit, or stop procrastinating and buy a new one.  Copper would have been my first guess too, but my test kit registers 0.

The crabs are (I think) red legged hermit crabs.

Do you use ro/di water to calibrate your refract?
or a salinity solution?

I use calibration solution.  I got it from BRS.  Like anything else, I assume I can trust it.

Yeah its quite strange that you are loosing hermits like that.

Tell me about it...