Shrimp suicide?

[cpyne]

This has now happened to both of my shrimp, on different occasions, so I decided to post. Shortly after I have rearranged the rocks (which I keep to a minimum), the shrimp acts erratically and swims all around the tank very fast (but I am almost certain it was not injured by the moving rocks, as I am slow and careful so that none fall). It also does not appear injured. Curiously, in both cases the shrimp has molted recently.

Afterwords, it picks a spot and appears to stab itself with two of its longer legs (I dont think this is normal... the legs go visibly inside the shrimp). The first time the shrimp died within a couple hours. I am now waiting to see how the second one fares, but due to the identical pattern, I expect the same fate.

In the future I will quarantine any shrimp when moving rocks, if I ever even get more shrimp, but I am mostly curious if anyone knows something about this, what caused it, or what specifically happened to the shrimp. (I already assume it was my fault, but not sure why)

I'll repost as to whether the shrimp makes it through the day.

Here's tank details:
72 gal with 2.5 inches aragonite/finely crushed coral mixture
70 lb live rock
in-sump seaclone 100
in-sump carbon/phosban filter bag
bioballs being cycled out
4x65 PC
I use RO/DI water for top-off and changes, but tank was bought used a couple months ago. Much of the water still has tap origin.

SG 1.024
Ammonia 5ppm
Nitrate 5-10ppm
pH 8.0 (workin on it)
temp 79 deg
Calcium 400ppm


Low Bioload:
Healthy 6" Sebae anemone
Mated pair of clowns
Mandarin Goby
20 blue-legged hermits
30 nassarius snails
1 (probably soon zero) fire shrimp

Thanks

 

[oscar83]

obviuosly your tank is not cycled yet. with ammonia of 5 ppm i wouldnt expect anything in that tank to live. how long has the tank been set up?

 

[cpyne]

Yeah my bad, I was misremembering the value on the card. It is actually .25 ppm (it is basically only one unit above 0 on the card). Still I have wondered why it doesnt stay at 0 like everyone elses tank.

Sorry for misinformation.

Anyway, it has been 8 hours, and the shrimp is still alive (although not moving around much from under the rock). Maybe it will survive after all.

 

[cpyne]

shrimp getting better

Well, impressively, the shrimp made it through the night and now looks healthy and active.

So is it normal for them to just impale themselves over and over with their legs (I mean it was really up in there!)

Harri Karri for shrimp...

Anyone seen this?

 

[bettagurl]

i have never had shrimp do that,mine are freshwater,but maby your shrimp are just suicidal.what other fish are in the tank?

 

[Crown Royal]

Fire and cleaner shrimp are extremely sensitive to fluctuations in salinity and pH, and cannot tolerate higher levels of nitrate (>5ppm). Further, you should have undetectable levels of NH4 if the tank is properly cycled.

From its behaviour, it sounds as if you may be going through mini-cycles resulting in the fluctuations. How old is the tank?

Mini-cycles can occur when re-arranging rockwork due to the amount of rotting detritus that gets kicked up and released into the water column. This in turn leads to higher NH4 levels (deadly to everything) and eventually higher nitrate levels (deadly to invertebrates such as shrimp).

Your hermits and snails also won't appreciate the ammonia and nitrate, but are less sensitive than the shrimp.

 

[cpyne]

Yes thank you Crown! I had not realized that arranging rockwork could do that, but that has to be it. There are probably pockets of ammonia and/or other nasty chemicals trapped under the rocks and sand that got released all at once. The shrimp could have been right at ground zero. Anyway, it's doing fine now and it has been a several days, so I am happy for that.

I have also been taking out 1/4 of the bioballs each week, to eventually get rid of them alltogether, so this could be setting up small cycles too.
I also have a mere SeaClone 100 skimming this tank, so that may to blame for the non-zero ammonia readings too. Im upgrading soon... hopefully I can find a used euro skimmer or reef devil. Anyone know of a place to look for used aquarium stuff other than ebay and craigslist?


The tank and substrate trace back a few years I expect. I bought it used with livestock included a couple months ago. When setting it up, I rinsed the substrate many times with salt water to clean it up some. It is probably still pretty packed full of organics though.

Other animals include 2 clownfish, 1 mandarin goby, sebae anemone, hermits, snails, and a cucumber thing. I doubt any of the animals are responsible... the clowns are quite tolerant of it and the hermits are too slow to do much. The anemone can sting I suppose, but the shrimp stays pretty clear of it (can't imagine why! haha)