I just posted pictures of it, are you sure that’s what it is? Zane do you know if there is any way to clear it?
Agree with the rest - Thanks for the picture - a couple questions:
1. Did you notice the spot immediately when you added it to the tank?
2. How big is the shrimp - i.e. is it a small one or more of an adult-size?
3. Do you know your water parameters - and what else (i.e. other shrimp) are in the tank - and are any affected?
4. Does the shrimp appear to be eating?
The reason for the questions - sometimes spots occur after a change in water and different chromatophores are expressed. Often this is a virus - a couple have been implicated - or a fungal infection. I.e. it seems to have more than one cause. With the end symptom being a 'black lesion'. As already stated - stable, excellent water quality is important - as is the fact that the shrimp is eating. Iodine levels have also been implicated.
On autopsy - many shrimp have been found to have 'empty stomachs' - meaning that have not been eating - so not eating is likely a poor prognostic sign.
Size-wise younger shrimp seem to be more susceptible.
Also remember that these shrimp are not long-lived - and this could also be a sign of old age (which is why I asked the size).
The good news - this often resolves after 1 or more molts. I would make sure the shrimp has great nutrition, is eating, and pristine water - as others have already said.
