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Little critters


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My display tank that does not currently have fish in it as they are still in quarantine, has abundant life in it.

Along with the plants came snails and limpets and some small swimmers. They range from .5 mm to as big as 1 millimeter and look like small gray beetles that move as fast as 1 cm per second scurrying along rocks and swim through the water column.  I might be discerning tiny antenna when I look with magnifying visor.  

there are a few on the white rock below.  Unable to figure out how to put a red circle around them in photo, but this is 2x magnification.

Unable how to attach a video of them moving.


Can anyone identify?


Will the fish be thrilled with live food when they get in the tank?  Is it something I might want to set up a tank to propagate for live food on an ongoing basis?


high ammonia and nitrite levels during initial cycling didnt seem to phase them one bit.



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Better picture maybe.

Here are two of them 2x magnification on gravel.

plenty of them crawling in and amongst gravel. Also plenty of them in Hornwort.

Are these scuds?

Plants do not seem affected, and since I cant keep any Shrimp in the State of Maine, Scuds would not pose a problem in that area.

If they are scuds it seems the only way to truly deal with them is to tear down the tank and start over and bleach dip all of the plants and bake rocks and subatrate.


The idea of doing this starting to cycle the tank all over again is not highly appealing…


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They really don’t look like the pictures I see for Scuds.


They do look like Ostracod photos, (seed shrimp). They definitely seem to have a shell covering them.


watching and examining closely with magnifying visor because presbyopia is a bear as you get older…


From what I have read so far, getting rid of them is like living in Groundhog Day…. A Sissyphian challenge.  They have survived the major extinction events….  Even nuking tank with bleach or CO2 doesnt guarantee success. Eggs can survive in dormant state for a long time.

anybody else have experience with them?




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Upon examining this new photo they look more like little snails to me.

Do snails swim in the water column?

These buggers also can walk across a rock fairly fast.  They move 1 cm in a second.  And the biggest one is about 2mm in length.

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Bladder snail can float through the water column. And they are fast moving on surfaces. 
My eyes are not great but they look like snails. 
Scuds are food and keep up with detritus. 
Most fauna we can SEE in our tanks provide some benefit to our ecosystem and are only occasionally predatory. 
What you can’t see with the naked eye has a much higher percentage rate at being detrimental and in a healthy unstressed fish a fishes immune system can fight many things. 
Hope that helps. 

Edited by Guppysnail
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These do not float through the water column they are actively swimming along at a good clip.  Its no water current as I shut off the filters to check.

I am pretty sure they are Ostracod, seed shrimp…


I ordered a seed shrimp trap to try to catch some.  Nothing like getting it on a plate to look carefully.




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Extreme Bottom wafers will be an excellent lure to get them in the trap.


I dropped one in next to the front glass and they swarmed to it within minutes.  

got to take a close look with highest magnification loupe on visor since they are close to the glass and engrossed in eating.


i can make out the split between the two shell halves and the antenna.


apparently Cherry Barbs and Guppys like to eat them and both were on my short list for next batch of fish after this batch comes out of quarantine.

gravel vaccuming, daily trapping and predatory fish combined has managed to clear them out of some tanks.

They are rather abundant right now, and I wouldnt mind seeing their numbers go down a bit.

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On 6/12/2022 at 8:08 PM, Pepere said:

Yes, that is a snail on the glass above the wafer, but those are clearly not snails on the wafer.



Oh my goodness, that is quite a swarm. I had seed shrimp in one of my tanks for a while, but not that many, and eventually they disappeared. The tank only ever had guppies in it, and the seed shrimp were there when there was the original trio of guppies, but by the time the first fry had matured to adults of breeding age and I had a handful of adults and 40+ fry, no more seed shrimp. I was sad that they were gone because they were cute to watch buzzing around--their erratic swimming patterns reminded me of bumblebees.

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I have been Fishless cycling the tank. Dose with 2 ppm ammonia, wait until nitrites disappear and do it again.

As such nitrates had been plentiful and so was light.  Great plant growth, and also some algae at times that settled to the bottom of the tank.

I wasnt worried about the nitrates since there were no fish in the tank, and Algae was not too noticeable.  But it clearly has given these fellas plenty of food, and currently they have no predation.


that will change in a few months.

Once this current dose of Ammonia gets metabolized, I will give the substrate a good vacuuming and fill water back up. 

by Thursday my traps will be in and we will see what we can do to knock down numbers with that.

In four weeks I put current quarantine fish into this tank and get second batch to quarantine.

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My guess is that they would reach homeostasis.  Breeding would continue until carrying capacity is reached. That being said you can get an awful lot scurrying around in and on the substrate.

They  are reputed to be a good cleanup crew eating algae and decaying plant matter.

They are live food for some fish that enjoy the wriggling and jiggling.

there is some concern they harm baby shrimp and can harm snails by nibbling on their mucous.  My hitchiker snails dont seem the least suppressed…

I have read of some concern that some fish have also been harrassed by them..

Bioload is not likely to be huge as the biggest ones are under 2 mm.

At this point, I am okay with having some in the tank, but want to cut down on the population.

Tomorrow morning, I will be doing a good vacuuming to reduce available food siting on the bottom of the tank, and mechanically removing a fair number of them through the vacuuming.

Trap should be delivered by weekend.


4 more weeks and first batch of fish will come out of quarantine and be introduced.

I suspect the Dwarf Gourami will enjoy stalking and consuming some.



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On 6/21/2022 at 9:16 AM, Chick-In-Of-TheSea said:

Hey @Pepere!  You know, I think those things might be limpets. @HenryC Do you think so?

I'd say these are seed shrimp, because he said they move quite fast and swim around. The limpets are kinda slow and only stick to surfaces.

Got all these critters in my shrimp tank. Seed shrimp, detritus worms, planaria, hydra, limpets... you name it lol. Check out the micro worm on my video, these are so tiny I never noticed them until I filmed with macro lens: 


Edited by HenryC
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On 6/21/2022 at 12:05 PM, Chick-In-Of-TheSea said:

That was such a joy to watch @HenryC.  You take time to enjoy the little details.  Everyone respectfully shares the broccoli. Was that the microworm at 6:03?

Thanks and yes, I think those are detritus worms. They're eating shrimp king food, but it surely does look like broccoli lol!

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