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Shrimp population issue?

3K views 15 replies 5 participants last post by  Blue Ridge Reef 
#1 ·
After months of struggling for happy, healthy neo shrimp, my little Fluval Spec III seems to have hit a stride. Java moss and ferns are all filled in great, algae is under control, and the tank looks awesome.

Before, my shrimp (4-7 of them) would last a month or so and then randomly die. Recently, though, my two big female Red cherries are going strong for many months, and one plain dull white male made it long enough to get each one to have babies. A large amount of those two batches have survived (interesting that my betta doesn’t ever bother them), and now I have about 20+ adolescents.

Yesterday, I noticed another new batch of tiny babies, which is the result of one of the deep blue color males and the big red cherry female. I’m excited to see how that coloring pans out for the babies. The babies of the white and red parents are a huge variety of mix of plain gray/white to speckled red, to heads that are white and body that’s is red, etc etc.

Anyway, I’m thrilled the tank is happy now, but, it also doesn’t seem too realistic to have 30-40 shrimp in a Fluval 2.6 gallon. In this sort of situation, does nature sort of take care of itself and only X number will end up thriving and surviving? Or will it be potentially some other real issue that needs to be controlled in some way by me physically removing them to avoid tank waste overload or something?

Thanks!
 
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#2 · (Edited)
Good to hear your little shrimp tank is working out for you! :)

Interesting question regarding what limits shrimp population. I keep seeing 2-5 shrimp per gallon mentioned. I currently have two 13 litre shrimp tanks with about 15 shrimp in each, one RCS and one CRS, with lots of Christmas moss, cholla wood and hiding places (see link in sig). To be honest, the shrimp are pretty lost in there, so I'm wondering where the recommended stocking levels come from?

Shrimp have small bioload, so it's presumably not a filtration issue. My shrimp don't appear crowded - actually far less crowded than in the big breeder tanks you see in Youtube videos where there are hundreds of shrimp swarming over the feeding dish! I have lots of moss with lots of hiding places, so it seems each shrimp can get away from the others when needing quiet time to molt etc.

Maybe the limiting factor is to do with how much biofilm / algae your tank can support for the shrimp to graze upon? If so, is surface area (of all substrate, glass, moss, leaves, wood, etc) perhaps more important than water volume?

Really not sure, but hopefully someone more experienced can offer some thoughts....

Regards, James
 
#3 ·
Thanks. My large nerite went on an adventure and died outside the tank and he was a huge bioload from what I could tell. Regardless, I do a ~40% water change each week and the stuff I pull out is very smelly and a good amount of shrimp waste. As beautifully clean as the tank looks, I can’t imagine leaving that junk in there more than one week. When the babies grow to adults, I wonder if semi weekly will be necessary. Unless Darwin kicks in strong, I could honestly have 40 shrimp in the tank not counting any new broods by the time these all grow up.

The shrimp are very actively grazing but I also put about 1/4 of a little disc of shrimp food in there about twice a week. It’s a “YouTube esque” feeding party when that happens.

It’s almost comically tragic with my old betta. He’s about 3 years old, and used to puff up and hammer the first few neo shrimp when they’d get near him. Now he just sits back and looks defeated when 30+ shrimp are all around, 5 at a time up on his resting leaf lol. Occasionally he puffs up, but I’ve never seen him strike at even the tiniest babies.
 
#4 · (Edited by Moderator)
You mentioned that the stuff you pull out is very smelly. Just wondering, what is this stuff? You mean shrimp waste, or is this perhaps dead plant and/or algae matter? I'd be surprised if you have so much waste from the shrimp as I can't detect any from my 15 or so critters, so even 2 or 3x the waste would still seem less than you're talking about. I only have moss (Christmas moss I believe) in my tanks which I love because it is so low maintenance and there is virtually no decaying plant matter to deal with.

40% water changes each week seem big. I know RCS are at the hardier end of the shrimp family, but they still need stability. If you're having deaths, maybe give some thought to if the big swings in water parameters with big water changes could be an issue. Honestly, my tank really came together once I started to RO water, switched from Equilibrium minerals to Salty Shrimp (much lower TDS), and reduced water changes to less than 10% at a time. If you need more water changes, better to do more small ones than one weekly big one. But ideally, the fewer and smaller water changes the better to keep everything stable.

Also, snail poo = shrimp food. My tanks are (unintentionally) full of about 10-15 Malaysian Trumpet Snails each. I like them so they're welcome to stay and keep the soil aerated, plus give the shrimps something to graze on. I'd definitely recommend some sort of snail in a shrimp tank.

Have you come across Marks Shrimp Tanks on YouTube. Scottish shrimp keeper living in Norway. Worth watching his videos of water changes, feeding, tank setup and maintenance, etc. Some good pointers there for sure.

Hope this helps anyway, but fingers crossed an expert will be along shortly to help set us both straight! :)
James

Also meant to say, maybe consider 'upgrading' the filtration in your tank. Seems pretty decent already, but maybe gradually switching the bio-media to Seachem Matrix might help boost bio filtration. And adding some Purigen will help remove organic matter before it has chance to decompose, hence reducing the need for big water changes. Just a thought...
 
#5 ·
You can stock a tank with 3-5 per gallon but if you feed, they will breed. The good news is, they won't reproduce past their resources, so being stingy on food can keep numbers in check. I have had several hundred shrimp in a 10 gallon, and as long as everything is kept to their liking a tank can support that. It does seem that when numbers get that high that shrimp tend to stay on the smaller side, in my own tanks when there are fewer in the tank is when they reach those 1"+ sizes. I've seen others on here report that wasn't their experience but it's been pretty consistently mine.
 
#6 ·
Interesting comments, thank you.

As far as the water change...honestly on the 2.6 gallon Fluval Spec, I’m doing a 1 gallon bucket, that that happens in about 20 seconds. It’s tough to do less.

As far as the smell, it’s classic waste/sewage smell and what comes up from the gravel is definitely tons of little shrimp poos, to use a technical term.

Sadly I’ve had to take time to let the bucket settle and let the poo drop so I can see what little shrimp babies got vac’d up and try to net them and get them back home. Really want to see how these red/blue babies come out!

I agree that the snail poo could be decent shrimp food, but they sure seem happy grazing on all the moss and ferns and cholla wood, and then the bit of food pellet I give them 2x a week.

Interesting about the size of the shrimp related to population. I bet I will notice that. When I was down to just the 3 female cherries (now 2), they got BEEFY. Biggest cherries I’ve ever seen by far, in person.
 
#7 ·
As far as the smell, it’s classic waste/sewage smell and what comes up from the gravel is definitely tons of little shrimp poos, to use a technical term.

Your substrate shouldn't stink. With 200+ cherries in a 10 gallon, the substrate never got *that* dirty in a week's time. I have to guess that's uneaten food more than shrimp waste.
 
#8 ·
With a fish in the tank, doing larger water changes probably isn't a bad idea...

When it comes to shrimp, I agree, "less is more" is generally a great method to follow! Although some people have no problem doing 50% water changes 1-3 times a week on their tanks, quickly emptying out that water and refilling it just as fast. Other people have had to tone it down to doing 10% water changes once a week and dripping the new water back in to prevent deaths. In short, what each colony can handle may vary from colony to colony...


Given enough food and clean water, it is possible to have a several hundred in a 10 gallon tank! Maybe even a thousand! That said, it's generally recommended to have larger tanks for shrimp... 5g a minimum, but 10g or larger is what's best. The reason being is that smaller tanks can fluctuate more in parameters than a larger tank, thus making them more difficult to maintain. Just something to keep in mind.
 
#10 ·
Not trying to be argumentative here, but 20ish shrimp shouldn't produce enough waste to stink up substrate in a healthy tank. I water change shrimp tanks every week of my life, having 11 of them and I can't remember the last time one had a noticeable odor. This makes me worry that water flow is lacking and anaerobic bacteria are building up or perhaps the cycle of the tank is stalled. Things obviously aren't going too wrong seeing as your numbers are increasing but siphoning off foul water is a troubling sign. Any chance some plants have died and their root systems are decaying or something along those lines? If not uneaten food or dead bodies, something would seem to be decaying under there. Small tanks like that are difficult to fully gravel vac because as you said, the tank is empty before you can get 20% of it cleaned. But I would endeavor to get it as washed as you can. If you can siphon some directly into a bucket (without the gravel vac attachment) or net it out manually and rinse it in dechlorinated water that might go a long way. Trick there is avoiding sucking/netting out baby shrimp, which would be no small task in a 2.6 gallon.

How deep is your substrate? Any chance you could post a picture of the tank? Just trying to troubleshoot here, and sometimes a photo says 1000 words.
 
#12 ·
Thanks. I’ll try to post a pic of next week’s water change bucket. What it is is about a 0.9g bucket and when I vac water into it, tons of tiny shrimp poos will be in it and settle. It’s not decaying plant roots or matter since they are all uniform little poos lol.

Vac’ing the babies has been and issue no matter how hard I try, but I’ve managed to rescue them back from the bucket into the tank.

I agree on the smaller diameter vac hose. I am doing a couple of other things that help. On my (approx) 1/4” vac tube, it has a pinchy sort of slide plastic piece that I have all the way “on” so it restricts a ton of flow. Still, it drains it very fast. So, I then let any smaller gravel bits that get sucked into the vac but then jam up against the restriction clip stay there. That really slows it down to a manageable flow. Eventually those gravel pieces come loose and drop out, so it isn’t perfect.

Speaking of the gravel, that could be another reason for my sort of situation. Since this was really a betta tank that I added a few shrimp to, it just normal 1/16” a 1/8” aquarium gravel, not a real sand/natural base substrate. It probably lets a ton more shrimp poo lodge way down at the bottom between the crevices of it all, rather than staying sitting on top of a finer type of substrate?
 
#13 ·
Here is a picture of the water after a 10 day change. Close up of the shrimp poos on the first one
 

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#15 ·
What about trying some bacterial supplements (e.g. Seachem Pristine). Not the bio-filter starter type, but the bacteria to break down excess waste and sludge in the tank. Still seems odd that your water smells with such a small load of shrimp, but maybe there is something not quite right with the substrate that is affecting the way that waste is being processed and decomposed? Maybe you're missing the right type of bacteria, or have some sort of wrong bacteria? (thinking along the lines of boosting good bacteria / reducing levels of bad bacteria in your gut by drinking Yakult etc as an analogy).

When you find a reason / answer / solution, please make sure your post here so we can all learn something! :wink2:

Kind regards, James
 
#16 ·
I'd wager my favorite aquarium that what you're seeing there isn't shrimp poop. Or at least not the majority of it. They tend to poop in light brown strands, for lack of a better word, rather than solid particulate spheres. Not my photo, but here's an example of an unusually long strand. They almost always break before they can reach such a length.

You can't even vacuum one up without it mostly dissolving in the turbulence. I'm thinking there are bits of substrate, uneaten food, various detritus, and a small amount of fecal matter in that mix. But the more concerning thing is that it has a foul odor. There would seem to be some anaerobic breakdown going on somewhere in your substrate.
 
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