What’s Causing This Shrimp Sickness?


Hi, y’all! I’ve just had another shrimp come down with a mysterious ailment, and I was hoping y’all might be able to lend a hand. A few days ago, I noticed my largest Red Rili shrimp (a female who laid one batch of eggs previously, shortly after the power outage and multiday freeze in February) has developed a milky white ‘core’, so to speak, where her tail has a defined white bar running through the middle of it. I believe this is probably muscle necrosis, considering the tail seems to be a bit cramped and some of her back legs now hang down limply. I’d unfortunately seen this before: the red rili mother that started the tank died from almost identical symptoms a few months back, though she seemed less motile than the current shrimp and died within a couple days of my noticing the issue. Notably, a mature RCS - the only other shrimp in my tank to have reached the size of the two aforementioned rilis - died a few days after that, possibly of the same issue (I couldn’t confirm, due to the RCS not having a transparent tail). Anyone have any idea what might be causing this, or how to save my shrimp? Is there possibly a reason why it has apparently targeted only full-sized shrimp so far?

~The Template~
Volume: 10g
Time since setup: 8 months
Filter: Sponge filter, rated up to 40g
Heater: EHEIM 50W in the winter, none needed in summer
Temperature: 78, as of writing this post: planning to turn down or take out the heater, as I’d like it a bit lower
Stocking: dozens and dozens of Red Rili shrimp across a couple generations, vast majority are either relatively small adults or shrimplets. (The F1 generation inbred with each other before I added more, so the shrimplets are the products of that...I hear it’s not that dangerous for them, but it’s certainly uncomfortable for me, lol)

Water change frequency: Ideally, I intend to do small changes once a week, but I’ve slipped on this lately due to life stuff and also not wanting to suck up babies (not exactly sure what my average time between changes was). Did a deep clean recently in hopes of resetting things. Top-up abt once a week with RO due to evaporation.
Water change volume: I’d guess 5-10% on average
Water treatment: I use RO water and then buffer with Shrimp Mineral GH/KH+.
Vacuum: I use airline to get the poop off the sand

Cycled: yes
Test Kit: API Freshwater
Ammonia: 0-0.25 ppm (it was that annoying in-between color that’s so common with API, shrimp behaving normally though so I’m guessing it’s closer to 0. If it’s higher it’s probably due to a recent overfeeding rather than a chronic issue)
Nitrite: 0 ppm
Nitrate: <5 ppm (I have lots of floating plants, so 0 nitrates isn’t unusual for me)
pH: ~7.4
GH: 7
KH: 2, possibly 2.5 (test doesn’t have the sensitivity to distinguish)
TDS: 226

I honestly don’t specially feed them, as there’s driftwood, live plants, botanicals, and of course the filter in the tank for them to skim. However, I did throw in an API bottom feeder pellet a couple days ago when I noticed the issue (in hopes of correcting things if malnourishment played a role), and again yesterday, and they ate those up pretty thoroughly - they seemed to totally finish the one yesterday.

Illness & Symptoms
How long have you had this shrimp?: I believe it was born last September
How long ago did you first notice these symptoms?: three or four days, I think
In a few words, can you explain the symptoms?: the “core” of the shrimp has turned a milky white, and is defined from the rest of the body. A few back legs hang immobile and the tail seems slightly cramped, like an upside-down v but much subtler.
Have you started any treatment for the illness?: I did a thorough cleaning and fed more often, but no medication.
Has the injury or illness been around since purchase?: Nope, the shrimp has lived in my tank its whole life and this is new
How has its behavior and appearance changed, if at all?: appearance changed as mentioned above, behavior has stayed fairly stable though, aside from some motility issues


Filling out that template is so important as you've done so thanks for that and helps with the diagnosis.
What you've described is one of two!
Muscular Necrosis or Cotton wool I suspect Muscular Necrosis as its started in the tail where cotton wool appears in the whole body at once.
The cause would be letting your water changes slip as its thought this disease is brought on by water perameters or chemical imbalance,, either way treatment is is not possible with any chemicals and death followed shortly after the whole body as turned white.
You need to start doing regular water changes to try and halt the spread, the one that's bad at the moment could be separated and treated with water changes on her own
50% water changes every 4 days for 12 days should help but this as its problems if its not done water at the same temp
Do your normal mix with minerals then stand the bucket in a sink of hot water to bring the temperature up to tank temp when this is done you can use jug to put about ½ltr at a time back in the tank, getting this right will not affect the shrimp but it must be right, if your unhappy doing this then do it slowly leave it run from the bucket through an airline onto the heater as this will come on if the temp drops.
  • Thread Starter


Thank you so much for the advice! I think you're right about the maintenance bringing this on - the shock of the freeze a couple months ago really upset the ecosystem of the tank, and my scattered schedule since then meant it took a while to even back out. I'll follow your advice and try to get things back in balance.

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