Sudden shrimp death

[Remi de Groot]

Hey all,

Came home to an Shrimp massacre today. In one of my shrimp tanks (left one on the picture) 7 out of the 10 Caridina Blue Bolt shrimps died, the last 3 are barely moving. The aquarium itself has a strange chemical (almost chlorine) smell to it what it didn't have before.

Thank has been running since begin november, shrimps added mid december. Except for 1 death shrimp couple days after adding them never had any other problems with the tank. Water tested good all the time and even with the funny smell and death fish i can't see anything strange in the numbers from the tests. Did it both with a drip test as with a strip (because i didn't trust the first results.

Tds 149 (normal between 130-140)

Ph 6,0

Kh 0,0

Gh 6

No2 0,0

No3 0,0

Nh3 0,0-0,5

Po4 0,0

Aquarium is filled with reversed osmosis water with some GH+ and ADA Amazonia 2 substrate to get the PH lower and in balance.

Someone that knows what could have caused the deaths and the strange smell to the water?

[colo3000]

Sounds like a small ammonia spike, which shrimp are especially sensitive to. The smell you describe also aligns with an ammonia spike. As for the cause of a spike I'm not really sure. Amazonia II does contain nutrients and therefore will leach some amount of ammonia, and if the substrate is disturbed you may experience more leaching. Weird that the tank has been going for months without this issue though if you haven't changed anything.

Edited February 8, 2022 by colo3000

[Remi de Groot]

I did add a new 'feeding corner' (don't know the english name for it) 1,5 week before the crash. So i did disturb a part of the substrate. Wasn't a big area tho, which would mean you can't really vacuum the gravel without a spike.

Smell was really strong eventhough i couldn't messure the ammonia. Smell was still strong after a 80% water change. But good to hear that the smell could be ammonia.

Last shrimps died the day after. So emptied the whole tank today and will start over with this tank soon i guess...