# Fertilizer: Toxicity to Cherry Shrimp?



## trag

I recently started dosing my tanks with an EI regime, which seems to have my plants back on the right track. However, I seem to have killed off all the cherry shrimp in my 30 gallon tank. This is not as bad as it could be because I have another (larger) population in my maternity tank. However, I would like to reintroduce shrimp into the 30 gallon tank and not kill them off again. I had been keeping the two populations separate to maintain some little bit of diversity, but I guess they'll all be one gene pool now, unless I buy separate stock for the repopulation.

Which of the typical dry plant fertilizers are most likely to achieve toxicity to cherry shrimp first? Will iron? I suspect iron because I was dosing CSM+B at a level that should achieve about .5ppm iron. However, I was also dosing chelated iron at about the same level. When I tested for iron early on, it always seemed to disappear quickly, so I think I got a little carried away with the iron dosing. But I suppose it could be the other elements in the CSM+B or the potassium or the nitrate. Or the sulfate in the potassium (K2SO4)? I only dose phosphate very lightly because it already tests fairly high in my water.

I do a 50%+ water change every two weeks but I went to three weeks this last time and that may have played a part as well.

I was dosing the maternity tank at lower levels than the 30 gallon tank and one day about a week ago, I noticed several shrimp on their side on the bottom. I immediately did a water change and later that day they were fine. At that time I checked the 30 gallon tank but the shrimp in there seemed fine. However, they're also harder to spot and there are fish in there (corys) who might eat a disabled shrimp before I could spot it. But I thought they were okay, since I checked and saw several shrimp doing their thing in the 30 gallon.

This weekend when I did my water changes, I could find no shrimp at all anywhere in the 30 gallon. So I think that whatever almost killed the shrimp in the maternity tank, killed off the shrimp in the 30 gallon, and I didn't notice until it was too late.

So I'm wondering which fertilizers I should use with more caution.


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## JohnPaul

Can't give a guaranteed answer, but some ideas:

First suspect when talking about shrimp toxicity is always, always, always Copper. Copper is just incredibly lethal to shrimp. I dose very, very small amounts of Flourish in my planted shrimp tanks--I mean, way less than the recommended dosage on the bottle, because Flourish has Copper in it. It is only 0.0001% Copper (one ten-thousandth of a percent!!!) and yet that is enough to make me extremely wary about dosing anywhere near the recommended dose. What is % copper in your CSM+B stock solution?
Iron is a possibility too. It certainly can be toxic to shrimp at high levels, but I am not sure how high we are talking.
Where do you keep your nitrate levels? From my own experience, anything over 20 ppm nitrate and you start seeing some impact on RCS and other _Neocaridina_ shrimp, especially in terms of less reproduction and fewer shrimplets surviving to adulthood. I am not sure exactly how high nitrates would have to be before they are outright toxic, but you can bet it is lower than the toxicity threshold of even highly sensitive freshwater fish.
Another thing to consider is your TDS. There is a lot less concrete info, but anecdotal evidence of shrimpkeeprs who have experienced population crashes (and I'm talking complete 100% mortality crashes) in a tank where the "water parameters are fine" seems to point to a growing body of evidence that TDS might be the cause; or in planted tanks, perhaps a combination of TDS and DOC's (dissolved organic compounds). If you don't have one already, you can buy a handheld TDS meter for under $20 from Amazon.com. Get one and measure the TDS of your tank(s) and compare it with the TDS of your tapwater (or whatever water you put into your tanks). If there is a big discrepency--by that I mean, if your tank values are more than 25% or so higher than your tap water--then you might be seeing an issue there. For me, my tapwater has TDS around 180-190 ppm, and on tanks I maintain well the TDS is usually around 200-225 ppm. On tanks where I've gotten lazy about doing water changes, it can jump as high as 300 ppm. I can't ascribe a cause/effect, but I can tell you that recently of my three tanks (all with _Neocaridina_ shrimp in them), the two tanks where TDS were 220 ppm and under the shrimp were reproducing fine, and the one tank where the TDS were 280-290 ppm, the females were no longer berrying and my population was rapidly dwindling. I can't guarantee that there's a cause-effect relationship there but I think it's an interesting observation, nonetheless. And in a tank where TDS are building up, usually you can assume that your levels of DOC's are building up as well, since both TDS and DOCs are only removed in one way: water changes.

Just some random thoughts. Hope some of them might prove to be helpful.


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## trag

Thank you JohnPaul. I will work your advice into my practice. I'm still trying to decide how to repopulate the 30 gallon with shrimp.


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## rod

Sorry to hear about your shrimp. I doubt that it would be the CSM+B, I dose that heavy for the Red Tiger Lotus in my tank and have never had a problem with the shrimp. I have dosed it heavy enough that it causes an algae problem and still causes no harm to the shrimp. Unless you are going way over the recommended amount I'd move that to the bottom of the list. I have had loses however when the nitrate level goes up, when I get lazy about water changes. Not sure about your tank but I've noticed in mine they seem to be very temp sensitive. 
Good Luck, and let us know what you find.


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## trag

rod said:


> I have had loses however when the nitrate level goes up, when I get lazy about water changes. Not sure about your tank but I've noticed in mine they seem to be very temp sensitive.
> Good Luck, and let us know what you find.


Thank you, Rod. I guess I'll monitor my nitrates for a while. I was planning to do that anyway. I'm still ambivalent about whether to dose any KNO3 at all. I was dosing some, and that along with the delayed water change may be what did the shrimp in. The 30 gallon tank in question is full of guppies, plus ten Coryadoras aeneus. So there's a very good chance that I don't actually need to dose any KNO3 at all.

The temperature is (or should be) stable. I keep a heater on that tank to keep it 76 - 78F because the guppies seem to do poorly below 72 - 74F.

Thanks again. I will keep an eye on the nitrates.


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## niko

Also keep in mind that your shrimp maybe fine for many months and one sunny day for no apparent reason they decide to leave this world. Dwarf shrimp are like that. In big numbers. That's true for at least 10 species of dwarf shrip.

No change of conditions, not even a water change. It's very frustrating.

I speak from my personal experience. 

--Nikolay


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## jedishrimp

niko said:


> Also keep in mind that your shrimp maybe fine for many months and one sunny day for no apparent reason they decide to leave this world. Dwarf shrimp are like that. In big numbers. That's true for at least 10 species of dwarf shrip.
> 
> No change of conditions, not even a water change. It's very frustrating.
> 
> I speak from my personal experience.
> 
> --Nikolay


I wouldn't say that they are dying for no apparent reason. Most species of dwarf shrimp are sensitive to changes in water parameters.. I have never seen large numbers of shrimp die off for no reason at all.. there is always a reason.

Are you injecting CO2? Are you over dosing excel? There are so many variables to consider.


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## Thorald

I have found that my shrimp start to do not so well when nitrates go over 10ppm. They stop breeding, move less and more of them die.

Try to keep you nitrates around 5ppm or lower.

Maybe you nitrates raised when you started dosing the ferts? Does it contain any N, P or K? The best way for me to contral nitrates has been by feeding less. If they don't finish all the food in a couple of hours you are feeding to much. Skip a day and feed half. It should be a feeding frenzy every time you feed them. The shrimp don't mind if you skip a day of feeding, they have enough bio film and decomposing plant matter to eat anyway (in my tank).


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## JohnPaul

To echo what Thorald said, watch feedings. I only feed mine about once every 3-4 days. All the other days they eat the biofilm that is in there. And when I do feed, it is in very small quantities, and usually either calcium-enriched (like Hikari Crab Cuisine or Ken's Fish "Veggie Sticks with Calcium") or else something like pure 100% spirulina powder.


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## trag

Thorald said:


> I have found that my shrimp start to do not so well when nitrates go over 10ppm. They stop breeding, move less and more of them die.
> 
> Try to keep you nitrates around 5ppm or lower.
> 
> Maybe you nitrates raised when you started dosing the ferts? Does it contain any N, P or K?


Well, keep in mind that the 30 gallon tank is primarily a guppy tank, so I could feed the guppies less, but it's not a like a shrimp tank where I can just skip days at a time -- I could, but they wouldn't be very happy about it.

Just a note for everyone, I found that my K2SO4 is about one part in 500 (maybe 1/1000) KNO3. I had two batches of the stuff and one was fluffy and the other crystally. The powdering stuff does not show any nitrates, but the crsytally stuff definitely contains some nitrates. It's probably too little to matter, but just the same...

And yes, I was dosing some KNO3 in the 30 gallon tank and that was probably a mistake. I imagine the fish were producing enough.


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## Big Dog

I do not put any fertilizerin my shrimp tank. My plants seem to be doing well. Just use fertilizer in my other planted tanks.


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## sampster5000

Have any of you tried Seachems Cuprisorb? I wonder how well it would remove the small amounts of copper put in from ferts like Flourish...


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