RCS tail missing!

[FishOwner]

So I just bought 20 RCS from an online supplier and everything was going fine. Today, I noticed a shrimp curled up under an almond leaf and I lifted it up to see if it was ok. It tried to swim away but it just flipped over and started swimming really weirdly. When I looked closer, I saw its whole tail gone. I isolated it in a beaker for further inspection. Some of the swimmerets closer to the tail are stuck in a swimming position and the whole tail is almost gone. There is also a black area around the severed tail area beginning to form. Can someone help me identify any issues?

The tank that shrimp was in is home to a few neon tetras and shrimp, along with 2 nerite snails. I had kept cherry shrimp in the same tank for weeks without any issues.

Here's a pic of the shrimp:
https://www.aquariumadvice.com/forums/attachment.php?attachmentid=317497&stc=1&d=1595442415

 

[Autumnsky]

It could have had a problem molting or after molting was chomped by a fish. Black part is likely necrosis.

Or possibly #7 Chitinolytic bacterial disease, Shell disease, Brown spot disease, Black spot disease, Burned spot disease, Rust disease
https://www.aquariumcreation.com/blogs/news/freshwater-shrimp-diseases

 

[FishOwner]

Probably has something to do with molting, since these are all newly bought shrimp. Do you think the neon tetras could have bitten the tail off? They get a bit excited around the shrimp e.g. pecking at the shrimp food and sometimes even swallowing it (no idea why). By necrosis, do you mean the tissue around the tail is dead?

Final question:
What should I do for it?




P.S. Thanks for answering all my shrimp-related questions!

 

[Autumnsky]

Watch in case other shrimp get a rusty color on them. Probably not this.

If it is rust /black spot, the link above goes above and beyond offering options from natural to antibiotic medication for the disease.

These options also mention ways to increase antibacterial / antifungal elements in the shrimp tank.

It might well be a nip from fish, causing the dying black part of the shrimps flesh. Infected and turned to a place where the flesh is damaged severely.

Or very possibly different explanation of the loss of the tail as the molt caught on the tail and ripped off when the shrimp got out of the old molt. In this case if the shrimp can stay healthy enough, he might drop off the dead part in the next molt and start to regenerate the new tail. It may take a few molts for the tail to get back.

How long has this tank been set up /running?

Do you ever vacuum the substrate? I would vacuum the substrate, mainly in the front where you feed the most often to get out any muck, old food. And also vac the areas where old food might collect, dead spots so to speak.

Don't do a really large water change (I wouldn't do more than 15-20%per day) this way / vac'ing, but gradually do more sections over the course of a week.

Getting a bunch of new water in the tank too, but gradually, will help the fish and shrimp in general, a refresh of the tank. Out with the bad - in with the new fresher water.

 

[FishOwner]

Ok. None of the shrimp in the main tank have shown any symptoms. The tank has been set up and running for about 3 months now. I don't really vacuum the substrate often, usually only to turn over the substrate every few weeks.

I think, for now, I'll just keep the damaged shrimp in the tank because it might get stressed out on its own.

 

[Autumnsky]

Sure.

If you happen to see any shrimp molts laying around in the tank, I would remove any just to be on the safe side. Usually you don't see them very often though.