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Gradual death of shrimp


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Hi - I'm wondering if anyone can explain what went wrong with my shrimp tank!

Although the parameters for ammonia, nitrate, nitrite were good in my small tank, the pH was high (8.2). This remained constant over a couple of months, so I thought it was ok. GH & KH were 6.

Then a couple of weeks ago the red nose shrimp, them this week the cherry shrimp and finally the nerite snails, died. I couldn't figure out the problem. Then today I emptied the tank. It was up on a bookshelf so normally I can't smell the water. Today when I siphoned it out I could smell a very strong chemical smell and the taste (a quick sampling when I siphoned), was tangy. Not like the earthy smell and neutral taste of the other shrimp tank I have. 

Any ideas what it could have been?

Edited by Macronano
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My initial guess for the smell wouuld be the dead snails (and shrimp, but less so) as they really stink and polute the water when dead. The PH and KH are outside the normal accepted parameters so that may have been what caused the deaths? The high KH may have caused the shrimp molting problems etc, have you seen any molts in this tank?.

How long had the tank been running, what water supply were you using, did you cycle the tank? Do you know the TDS, I suspect that will be a bit too high also.

It may have been a chain reaction from the first deaths poluting the water killing more causing more poluted water and so on! Did you have a regular water change/maintenance routine? Does the tank have filter/light/heater?

The more information you can give us the more we will have to go on.


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Hi Simon,

Thanks for the reply, apologies for not responding sooner. I saw lots of molts in the tank, from both the red noses and the CRS. They seemed healthy and fine. The only variation from their routine I can think of, just before the dying began, was that I got a free sample of Shrimp Snow from my shrimp supplier and gave them a bit of that.

The water temp was consistently 25 degrees, it was lit and had a HPB filter and the tank was running for about 6 weeks. It was cycled, and testing showed good parameters.

Reading your comments, I think maybe it was not doing weekly water changes that was the problem. Had I been more thorough, then I would have smelt there was something wrong. 

In terms of GH/KH, what should I aim for?

Thanks again for your comments.


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Shrimps don't need much maintenance and 10% water change a week would be normally sufficient, though if the water was poluted (dead snail/shrimp) a bigger water change may be needed! Add the new water slowly.

CRS shrimp KH 0-2, GH 4-6 and PH below 7. I would drop the temperature also to 23. As your PH is high I am assuming you may be using tap water and caridina shrimp rarely survive in that, you are best with RO water and shrimp remineraliser. You may be able to use a Zerowater filter jug to get RO water if the tank is small?

Over feeding is also a very common problem in the hobby? 


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@Macronano, test your tap water. Melbourne's tap water is usually very good for keeping shrimps. 

If your tapwater is lower in pH and KH, then something else is causing it to rise in your tank. Usually rocks.

Edited by jayc
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Thanks Simon and Jayc,

I just checked my tap water: pH 6.8; GH 53.7 ppm; KH 35.8 ppm - using API test kits.

For my next set up I will use river sand with a HOB filter, java moss and purple lava rocks and see how it goes. I'm also going to monitor the water for that chemical smell, and keep an eye on the GH/KH. I was thinking it was ok because the ammonia, nitrite, nitrate levels were good, but clearly there's more to it than that!


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1 hour ago, Macronano said:

GH 53.7 ppm; KH 35.8 ppm

That translates to GH = 3 and KH = 2 from your tap water.

Melbourne's tap water is okay for shrimps and softwater fish in general. 


So something else in the tank is causing it to increase to GH/KH 6 and pH 8.2.

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1 hour ago, jayc said:

That translates to GH = 3 and KH = 2 from your tap water.

Melbourne's tap water is okay for shrimps and softwater fish in general. 


So something else in the tank is causing it to increase to GH/KH 6 and pH 8.2.

I think it was the substate which was shrimp sand. I’m going to use river sand next time. And use less rocks. 

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21 hours ago, Macronano said:

And use less rocks. 

If you have rocks in the tank, then that is what is causing the water parameters to change.

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Really? Ok, I'm going to leave that out and maybe get a bit of driftwood. I started cycling the tank this afternoon with some java fern and hair grass because they seem to like hiding in that after they molt.

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