Nassarius Snails and Pistol Shrimp

[Instigate]

I have a bunch of inverts in a 5 gallon QT and some of the nassarius snails are acting strange. It seems like there is always two or three of them just laying on top of the sand bed with their foot out, their feeler appendage is usually out too. They have moved around the tank a bit and none of the other inverts are trying to eat them so I assume they're not dying. There is a pistol shrimp in there also so I'm wondering if maybe he's hitting them with his pistol claw and causing them to be stunned for some time after. I have 10 nassarius, 10 cerith, 1 conch, 3 emeralds and a pistol shrimp in there. All are acting normal except there being a few messed up nassarius snails all the time. Hard to tell if it's always the same ones because they're always in a different place. Anything I should check? Anyone seen this before? I did a 50% WC last night just in case there is some water issue but everything was the same today.

1.025
80 F
ph 8.4
NH3: 0

 

[Tahoe61]

I am going to assume everything is being fed?
Did you use any medications in the tank previously?

 

[Instigate]

I am going to assume everything is being fed?
Did you use any medications in the tank previously?

Yep, I'm feeding the tank plenty. No meds. It was a craigslist tank but it was used for FW before.

 

[Instigate]

4 of the 10 nassarius were dead this morning. Got them out and did 90% wc. Everything else is seemingly uneffected. I added 3 more conch yesterday and the two tiger conch are constantly mating.