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phishead
01-04-2020, 10:20 PM
For anyone not inclined to absorb the narrative setup that is about to come, feel free to skip to the bottom for the TL;DR version. But I do think the following retelling of the mystery is useful context.

About a week ago, I reinvigorated my little Fluval 5g Spec tank with several new inhabitants to accompany the residents of the existing community. The old guard consisted of 3 lampeye killifish, 1 RCS (the last of it's troupe), and a nerite snail named Gary. The newcomers included 7 chili rasboras, 3 c. hastatus, 2 amano shrimp, and 4 additional RCS. I also added several new plants to the tank when they arrived in the mail a day after the new livestock.

Though the tank was already well established, I recognized this was a somewhat significant restocking for the tank size and have, therefore, been keeping a cautious eye on my water parameters with daily tests. During this time, amonia has held to 0.25 ppm or less, with nitrites stable at 0 ppm, and nitrates have risen from between 5 - 10 ppm to 10-20ppm (leaning more on the lighter 10 ppm coloring). To be safe, I also performed daily water changes for the first couple of days, replacing roughly 20-40% (1 - 2g) in each change. All this to say, I was feeling pretty good about my water quality and the future of the tank.

But then, about 5 days in, disaster struck when I discovered my bigger, beefier amano to be a pinkish-orange corpse -- he looked... COOKED! I was of course sad, but also confused by the sudden death and color change. My first thought was that my heater had gone haywire, but everyone else was fine... I checked the thermometer and all was well. This being the case, I assumed there must be something wrong with the water -- I had in fact that morning also witnessed both amanos hanging out at the surface of the water by the filter intake -- but test results were consistent: little to no amonia, no nitrites, and reasonable nitrates. So here, the mystery begins. I don't think any of the tank mates were a bad pairing or would have stressed the shrimp. What had happened?

I began researching and soon discovered that the color change was natural upon death. So that, at least, was a relief. I further learned about invertebrates' sensitivity to copper, nitrates, and pH swings. Here I thought I might have a lead. My pH is actually a little high, ~7.4 - 7.6, due to the extremely high pH of my tap water, which I discovered is somewhere between 8.4 and 8.8. I also live in an old brownstone in Boston, which I suspect might have some copper piping; though, I generally run the water for a while when trying to match the temperature for water changes, so until my Cu test kit comes in, I'm reserving judgement on that. Finally, I think my nitrates are within reason, but I won't entirely discount that as a contributing factor.

Unfortunately, all this research did not result in actionable changes before my second amano was found on the floor the next evening upon my arrival home from work. Presumably, it had somehow escaped through the center whole of the tank's acrylic top. At this point, I had also noticed that the RCS were no where to be found, but have not identified any bodies. This increased my anxiety that something was wrong with the water, but again the standard tests showed everything to be within acceptable results.

After all this research, I'm mostly convinced that the frequent water changes with high pH tap water contributed to stressing out the amanos, and I assume the RCS have likely befallen the same fate. My plan for now is to dilute future water changes with distilled water, or to exclusively use distilled water. But I still have my concerns that there is something darker lurking in this mystery, and I worry about the safety of the other tank mates.

Is there anything that anyone here thinks I might be overlooking? Are there additional steps I should be taking to ensure the safety of my fish and reforming the tank into an environment that will be suitable for new shrimp?

TL;DR version:

I restocked my 5g tank with a school of chili rasbora, some c. hastatus, 2 amano, and 4 RCS. I was cautious about amonia, nitrites, etc. and did frequent water changes -- everything seemed fine. After 5 days, both amano's were dead and the RCS missing; though, the fish seem to be just fine. I think this is due to high pH water used in the frequent water changes (8.4+) vs the moderately high tank pH (~7.4). I don't think copper is an issue, but it's possible -- will know more when test kit arrives. Nitrates are ~10-20 ppm.

Is there anything else I should be considering besides using distilled water in my water changes, instead of just straight tap water?

Jetxx
01-05-2020, 12:26 AM
How old is your tank? Is it planted?

phishead
01-05-2020, 01:27 AM
The tank is several years old, and yes it's planted. Low tech, stock light.https://uploads.tapatalk-cdn.com/20200105/ca16671a50b7ae78a2899ee490bb4c66.jpg

Jetxx
01-05-2020, 01:36 AM
Copper might be an issue but can't be sure until your test kits comes.

RCS and Amano shrimps are kinda hardy, if you acclimatise them properly, they shouldn't have much problems.

Next I can think of is that your substrate has outlived its use and every time your shrimps dig at the substrate, pockets of ammonia is released and poisoning your shrimps immediately.

phishead
01-05-2020, 01:38 AM
That's an interesting thought. Though I did finally find 2 of the RCS today after my initial post.

AmandaYiu
01-24-2020, 08:48 AM
Copper might be an issue but can't be sure until your test kits comes.

RCS and Amano shrimps are kinda hardy, if you acclimatise them properly, they shouldn't have much problems.

Next I can think of is that your substrate has outlived its use and every time your shrimps dig at the substrate, pockets of ammonia is released and poisoning your shrimps immediately.

If the substrate was having pockets open up ... wouldn’t you have readings on tests??

SueD
01-28-2020, 06:56 AM
Not sure why I just saw this tonight, but.. I think I mentioned to you that my PH runs 7.4 -7.5 so I don't think that's an issue for your shrimp. Especially since your RCS came from my tank and I have 2 amanos in one of them. It's also common to not see shrimp very often when there are only a few in a tank with fish (potential predators). I only see my amanos when I feed certain foods.

I also don't believe that the substrate is an issue - mine is years old in all of my tanks - but you know that. But if your water comes out of the tap over 8, let it sit overnight in a container/bucket and then see what it reads. If it drops to 7.4-7.5, then you may want to age it each time before a water change if you continue to have issues with the RCS.

I hope to pick up a few amanos later this week, so if you want I can get a few extras that you can take back with you when/if you're in the area.