Jump to content

Recommended Posts


I have had a solid healthy line of bloody mary shrimp going for a few years that is darkening in color dramatically over the last few months, and I am trying to find out why.


One possible reason: about half a year ago I began hardening their water mostly due to losses in my snowball tank and partly due to our very soft water here in Portland OR. I have been hardening it with marine aquarium salt. I read the following article, and thought they might benefit from more mineral and salt content, and assumed the trace amounts of extra minerals in Kent Sea Salt would have a negligible effect.


The addition raises Gh to 5 or 6, Kh to 4 or 5, and salinity to barely detectable with a refractometer.


In the last few months I have also diversified their diet from primarily Sera pellets with a few trial runs of higher end stuff here and there to alternating Sera with assorted Shrimp King products. 


Since making these changes the snowball line has recovered and is reproducing, I have not seen mortality in the bloody mary line, but the bloody mary shrimp have darkened. The darkening is mainly in the back 2/3, not the head, and back stripe is not affected. So in many cases I now have jade green to black shrimp with maroon back stripe, occasionally one with vertical stripes. I also had a line of rili bloody mary's I was experimenting with and they when darkened are still fully clear within the rili pattern, so I don't think this is a pathology affecting internal tissue.


My question is, does anyone have knowledge of why this may have happened? Diet? Chemistry? I am going to isolate a group of them and reduce the mineral content over time through plain water changes to see what happens. In the meantime I don't know if I made an error not culling enough, or what. Thoughts?


Link to post
Share on other sites

I don't have any experience using marine salts with freshwater shrimp, for my caridinias I usually use Salty Shrimp GH+.  But I don't have to use it with Neos as my well water is fine for them.  It sounds like the study was doing that as the shrimp had parasites and they thought the salts would help...


How large is the tank?  Is it a larger tank?  Or a smaller one?



Link to post
Share on other sites

They are in a 5, a 10 and a 20L, all darkened. Not every shrimp in the tank but a significant number and possibly it's increasing. Took a couple pics, not the greatest but in the first one you see that almost black female on the right. 



Link to post
Share on other sites

It could be genetic drift...  Bloody Marys came from chocolates.  Looks like some of them may be heading back that way possibly.


Some of the ladies do turn dark as they get old.  Seems to only happen with the females.  I don't think I've ever seen it happen with a male.  I think it has something to do with pregnancy and hormones.  That at least seems to be the norm for me anyway.  So yes, some older ladies can turn dark, and opaque.  They kind of start to look more like large painted fire reds.  But that older female in the first picture (on the right) looks kind of brownish.  And there are some in the pictures that are way too young for that to be happening yet...


So I think it's just genetic drift back to chocolate.  I'd cull the darker ones, and only keep your best colors.  Then let the best colors breed back out.  They look pretty healthy though.


And I wouldn't bother reducing the mineral content.  They really should have a GH of at least 5 for good molting.  I keep mine at 7.  I honestly don't know how marine salts would effect them...  If culling doesn't solve it, you could try switching to minerals made for fresh water.  Salty Shrimp makes a GH/KH+ version and it's pretty cheap.  It's a dry powder and a jar lasts forever!





Link to post
Share on other sites

thanks... I do like the dark ones particularly with rili but I don't know if it's fair to sell them til I know the reason. Will check out the salty shrimp stuff. I have been so skeptical of mineral supplements after my years of reef keeping... shops sell a 1.5 cup jar of baking soda for 26 bucks if it has the right brand label on it. Ditto calcium, and super dilute forms of iodine.

I mostly tried this experiment because I didn't know what was killing the snowballs. Tried multiple tanks with a line that had been solid for years, and it was down to one pair, the female being very old. They are slowly coming back, estimate maybe half a dozen per month grow to adulthood. They would regularly die at all ages and be found next to a fresh moult so am assuming the two were related, and what survives is primarily female, suspect a genetic sex linked problem as in other white animals I have bred that sort of thing crops up... lethal genes in such inbred lines. Speculating of course. I don't see well so might not notice some parasites and I know the farms in Asia are getting high numbers despite not keeping them in optimum conditions (in some farms) so I figured I would do what the successful people are doing for a while. Also I like to experiment. I did try crossing out the snowballs to blue dream rili. Two generations in all I got were more snowballs. Guessing since their success at reproducing has been so low that if they did breed at all I lost the offspring.

I have a nice planted tank with no critters, will move the best of the reds to that and see what they do. The genetics thing though... didn't see dark young ones til suddenly there are many and of all sizes. I guess the dark ones can go in the rili tank.


Link to post
Share on other sites

I know what you mean about specialty stuff being $$$.  That's one of the reasons I like Salty Shrimp.  It's cheap LOL!


I've had bloody marys since 2013 or so.  Every few years I have to restart the colony because the color drifts.  Sometime around 2016 I restarted them because I felt I was culling too many light ones.  I restarted it again a few months ago because I felt they were getting too dark.  So, it happens.  I think it happens with all shrimp.  Even if we're diligent with culling, things can start to change after so many generations in so many years.



Link to post
Share on other sites

I have been experiencing this in my painted fire red colony as well. Lots of darkening recently in large females so this info was very helpful to read, thank you! I've had the colony a few years now and only twice have introduced a few new fresh shrimp. So I'm sure it's genetic drift for sure. 😕 

Link to post
Share on other sites

I've seen this in my low-grade bloody maries as well. It happened when I moved them from their preferred parameters into more of caridina parameters. Over time they eventually turned brown/black (and a lot of them died off). 


Not having put in the effort to isolate and reproduce this, it just seems like a stress response. 


It sounds like you have a good understanding of water parameters so I'm not sure what is triggering the response, wish I could be more helpful there. I would suggest swapping reef salts for Salty Shrimp GH/KH+ for lack of anything better. I'm skeptical of drift since the time period is too short, that wouldn't just pop up on a couple months.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...