I have 5 CBS mischling-or-something type shrimp (sorry, new to this lmao, I know they look like CBS but have a variety of genes). I had 10, but 5 died within a few days of getting them due to a battle with toxic substrate (sand and potting soil--I know the toxicity to be almost certainly true because at one point I poked the substrate, and minutes later shrimp were falling over dying). I took them out, set up a new tank with no dirt, just sand, and put them in.
They've been doing fine for about a week now, but now another has died. This shrimp was the runt of the batch at ~14mm; I noticed it was doing poorly when another one of my larger, seemingly healthy shrimp was on top of it and jerking it around, maybe trying to eat it, IDK. It was still partially alive when I found it--moving when I poke it--but now it's died completely, or at least enough to be nonresponsive.
Notably, I also have two Corydoras habrosus
(I know I should have more, I did and they all slowly died off from I think the same substrate issues, but I plan on getting more soon).
A couple culprits immediately come to mind:
- Overfeeding. My cories were getting antsy yesterday, so I gave them some sinking pellets. I saw three shrimp holding pellets, which are small but still pretty large for dwarf shrimp. I don't remember if the runt was one of them, though. Could it be too much food that did it in?
- The cories getting aggressive. One of my shrimp is swimming around... Not sure if that alone is something I should be concerned about, but I saw one of my cories actively chasing it. I haven't witnessed aggression from them before and I was under the impression that habrosus cories were safe to keep with shrimp. Could they have attacked the shrimp? Should I remove them? Would lacking a proper shoal be cause for aggression?
I'm, of course, also wondering if I'm not missing something here. Here are things I've mostly ruled out:
- As far as I can tell, there's no hydra or planaria... I did see one (1) planaria come out of the filter when I was first setting up this tank, and I promptly killed it outside of the tank and flushed it away. I haven't seen any more before or since.
- I don't think it's a molting problem, or shouldn't be, because I've literally seen these shrimp molt in this tank. They came from parameters very close to, and actually with higher GH and KH than this tank even though that's largely unheard of for CBS. I acclimated them all very slowly. I have no reason to believe they're not well-acclimated to these parameters.
With good reasoning, though, I'd be happy to consider those issues.
My parameters are:
- Temp: 71 degrees F
- TDS: 173 ppm
- GH: 6 dGH
- KH: 2 dKH
- Ammonia: 0 ppm
- Nitrite: 0 ppm
- Nitrate: I think like 20 ppm? I'm so bad at reading the nitrate results. Is that too high? I did a 20% water change a few days ago...
I dose PPS-pro fertilizer, 1mL each of micros and macros 1x/day. I haven't dosed yet today. I'm not dosing CO2.