cant keep cleaner shrimp alive

[pallan]

about a month ago both of my cleaner shrimp died I thought i had an ammonia problem but that turned out to be a false reading
added another cleaner two weeks ago and he was happy and seemed healthy now he has disapeared only found bits and pieces that i though was a molt but have scoured the tank and he is no where to be found
the original cleaners had been in the tank since shortly after set up/cycle completed and had been fine several months
1) the only addition to tank since just prior to the others dying was two emerald crabs. 1 of them is green the other is a brownish color, are they attacking my shrimp.
2) or is there a desease in my tank all three seemed fine but did have some black spots on side from time to time which i could not figure out.
45 gallon fowlr
yellow tang (i know to small of tank had not discovered this site by then)
1 firefish
2 emerald crabs
snails and small crabs
amm 0
nitrite 0
nitrate 10
ph 8.5
salinity 1.026

 

[pallan]

oops also have a peppermint shrimp in there as well forgot about him as i never see him unless i look close in his hole. He lives in same rock as the emeralds from time to time and a firefish no one seems to bother each other.
there is probably 20+ pounds of Rock need more but LFS to expensive 10.00 a pound and dont want to go through curing process from online order yet but will eventually.

 

[bang guy]

If the new Shrimp a lot smaller than the existing Shrimp the larger might be eating the smaller.

 

[dea_mt]

either that or i've actually had large emerald crabs prey on a cleaner shrimp and 2 clownfish in a small system...i know now to try to stay away from having any kind of crabs in my system. snails are a lot better IMO because they don't pick at stuff. i've also seen a sally lightfoot crab start ripping up a bunch of zoos! saw it w/ my own eyes, perfecly healthy zoos [open and all] then the SLF crab walks across em and they close and bam! i hate damn crabs

 

[hot883]

Could the S.G. be to high? Are you testing with a refracto or hydrometer? I had the same problem. My S.G. was 1.030 and my cheap swing arm hydro said 1.024. Just my experience.

 

[drea]

i had the same problem, two died on me within a day... the third one was perfect...
remember that shrimp are very sensetive to salinity changes...
i acclimated my last guy slowly for almost 3 hrs, worked great! it will work if you do that,,, and try to get one on the bigger side if possible

 

[pallan]

yeah i need a refractometer my elcheapo hydrometer reads 1.026 and i tested it with the LFS more accurate hydrometer to calibrate, but still im sure a refractometer would be best. but wouldnt the pepermint shrimp suffer to if it was water quality he still alive and kicking and not an issue through the other three deaths.