Where have all the crabs gone?


New member
All crabs and shrimp have dissappered, Hermit crabs,Green emerald crabs, sally lightfoot, cleaner shrimp, coral banded shrip all gone! No other noticeable problems. I started doseing iodine
but I'm hoping someone has seen this or knows whats going on!

3 tangs yellow, blue, purple
1 cromis damsel
1 yellow band marron clown 7 years old (Tank owner I'm just the maint guy)
1 cardnal
1 dimond back goby
SPS, LPS and Softy corals

125g reef 7 years, 150lbs rock
3 275w MH lights , skimmer, refuge, uv, calsium reactor, kalk reactor, RO w DI no other suplements

cal 500
alk 8-9
mag last test 1400
ph 8.2
temp 78-82
sal didn't check
I've had this so long I check stuff and don't think about results
unless they are off.


New member
Not sure I did'nt notice at first. What caught my attention was about about 10 days ago cleaner and coral banded shrimp were there at feeding time. The next morning they were both missing took about 2 days to decide they were gone then 2 days later the sally lightfoot looked like it molted but I have'nt seen it since.
Thats when I realized all crabs gone! there are shells lying around, I have'nt picked any up to see if their just dormant or gone.


New member
have you added anything new to the tank recently? say like in the past few months...rocks corals? maybe a hitch hiker took them out.


Premium Member
did you add too much iodine? Generally you don't need to dose iodine to the tank, its such a small part of the chemistry it's easily replaced with water changes and no further dosing. Rule of thumb: don't dose what you don't test for.


New member
I was not doseing iodine untill a couple of days ago when I started this thread. Now hermit crabs are starting to move around
I used to dose iodine many years ago when I first got my calsium reactor. I stopped doseing a year or so ago because like you I did'nt think I needed to. And I had no problems untill now. I don't do regular water changes.