Shrimp bits

Disclaimer: Yes, I know my tank has algae.

So, I peaked into my tank with cherry shrimp and Endler's today. Sadly, one of the shrimp was dead. Well, not just dead but with the front half missing. I have no idea what happened to the missing half of the little critter. It was clearly fairly recent, as it wasn't decomposing yet. The Endler's have never been particularly aggressive with the shrimp, and the other shrimp in the tank look content, eating, and not scared at all. Sort of a mystery. It's like a shrimp horror movie.

I can't really tell from the picture but it could be a shed part of an exoskeleton. Have you counted your shrimp and is that piece hollow? Endler livebearers aren't big enough to chomp a shrimp in half I don't think.

Oh there was shrimp meat in there! And, I do get that the Endler's are unlikely to chomp a shrimp. It just seemed odd.

Sadly, I just found another dead shrimp in the tank. Whole this time. The rest of the shrimp are feeding and doing fine, including the babies.

Ran all the water parameters. No ammonia or nitrites. Nitrates at 10ppm. The pH has been going up, so I've been changing more and more water; adding RO which comes in at 6.5. This has decreased the hardness some (and of course I'd expect the hardness to decrease by changing out the water with RO), but not as much as I would expect by dilution. On top of that, the pH is even higher now, at 8.4.

I'm wondering if I'm hitting pH they are finding stressful. I'm going to do another drastic water change again tonight, but it seems to help for less and less time each time I do it. And nothing I do seems to curtain the rising pH.

In another thread, I expressed that I have my suspicions that my rocks are an issue. However, they didn't react to HCL (muriatic acid), and the pH soak test is on going. The other thing it could be, I suppose, is heavy metals. I don't know. I'm grasping at straws here.

The thing is, this is bringing back bad memories of this tank the previous time I set it up. I had the same population of Endler's, and CPO (orange dwarf crays). After the tank was set up and cycled for 3 months, I put the livestock in. Then after about 6 months of them being in there, the CPO all died within about a week. Including the babies. Nothing changed with the water parameters that I could measure. It was baffling. Then, about 2 months later, same water conditions, all the plants started dying. Until everything but the anubias and a little java moss was dead. That was devastating. The Endler's did fine. Nothing seems to stop them! Still, I tore it all down and started over. Now, it seems like I am on the same path again.

Not sure I expect anyone to solve this, but I've now got even more water tests I can do, and except for the pH, nothing seems amiss. If it's the rocks, I have to tear it all down again anyhow. But, if I can't identify why this is happening, then I can't make improvements. I don't want this to become a vicious cycle. I suppose I am just frustrated and venting to people who I hope understand.

Ugh!!!!!!!! Okay, that felt good. Now off to change the water again.

Hmm well then sorry bro! That doesn't sound fun.

Thanks! That actually helped.

Did a 50% water change tonight. I'll take measurements tomorrow. If it did nothing again... I'm prepping quarantine tanks so I can tear this down and start over. Can't give up.

Did you get around to testing the rocks?

Edited to add: is there copper in that rock composition?

In process, as buried in one of my too long posts above.

Summary:
Muriatic acid test - non-reactive
pH drift test - in process

Copper?! Copper! That is a possibility. We have copper in this region (rocks at yards are mostly regional because of transport costs). Not super far from here you can even find native copper (i.e. chunks of pure copper just lying around in rocks). Hmm. Looks like I need yet another test kit. My aquarium water is going to end up being more tested than my well water. Though nothing is stopping me from doing that now too.

For anyone watching the saga of my dying shrimp unfold... I found another dead shrimp in the tank this morning.

Testing revealed that my 50% RO water change yesterday, again dropped the hardness but did not really impact the pH. I know pH is a log scale, but this is still baffling to me at some level.

That said, the rocks in there are not helping the situation. After letting them stew on my boiler in RO for 5 days, they increased the pH from 6 to 6.8, the TDS from 0.4 to 59.3ppm, and the GH from 0 to 25ppm. So despite not seeing any visual reaction to the muriatic acid, they are leaching some sort of minerals.

I did a K test, and it sits at 15ppm, so unlikely to be contributing to the high pH as was proposed. I've ordered a Cu test online, and plan to run that once it arrives. Frankly, if it is not copper, I fear disease.

This has played out so similarly to the crayfish die-off that I suspect I didn't get the tank clean enough after I reworked it. The shrimp even look to be dying the same way as the crayfish - no signs of stress, feeding and breeding, then just sitting there dead the next time I look in.

Has anyone run into crustacean diseases? I'd be curious to hear about any experience.

Also, what's the best way to sterilize an acrylic aquarium? Do you think I can put the fish back in with any crustaceans ever again, or are they suspect now? Last time the tank had no crustaceans in it for maybe 4 months before I cleaned it out, and then I let it sit dry for another 3 months, after which I cleaned it again before setting it back up to cycle for a few months. All of that doesn't seem to have done enough though. Perhaps I need to give up on crustaceans in this tank?

I'm open to any and all suggestions about what is happening and what I could do about it. Thanks!

How long have the shrimp been in the tank?
Have you used any meds in the tank?

4 months with the shrimp in the tank. No meds.

Only things I've added intentionally besides RO during water changes:
regime of 1/4 recommended Aquarium Co-Op easy green liquid to feed the plants (had no nitrates)
4 Seachem Flourish root tabs (it's a 42 gal tank) about a month ago
H2O2 to combat staghorn algae (last done several weeks ago)

There IS a small amount of soluable copper in those root tabs...and if you find out your source water may contain traces of copper....not good for inverts, as you know

For sure! I'm hoping that the copper test will help shed light on that. It would be a bummer if the root tabs killed my shrimp. That said, I have to imagine that this has been tested. Although, I often imagine diligence should have been done and was not.

Well, I have a copper update. After testing with the Seachem copper kit, I found no detectable level of copper. This means I suspect it was not copper, though I can't be sure.

The lack of certainty is because I did some massive water changes, which seemed to work as the shrimp have stopped dying. Had it been copper killing the shrimp, I would guess there would be some detectable levels in the water column at this point because I have not done a water change in a couple days now. But maybe that's not enough time for it to build up? So, it's hard to know with a high degree of certainty.

Because the shrimp have stopped dying, I no longer suspect a disease organism was causing the die off. My best guess at this point is that I must have done something or handled something and then put my hands in the tank. That's all I can think of at this point.

I plan to change two things based on this experience. The first is that I need to be far more cognizant of washing my hands thoroughly before putting them in the tank, always. And secondly, I intend to cease using the Flourish root tabs that have copper in them (thanks @eatyourpeas and @Slaphppy7 for both suggesting copper and pointing out its presence in a product I was using, that was very helpful!). Hopefully those two changes will avoid problems like this in the future.