# What are these little creatures in my aquarium?



## ddiaz28 (Jan 8, 2013)

I've noticed quite a lot of these crawling around in the substrate of my tank. I always suck up quite a few whenever I do a water change. Anyone know what they are and whether they are harmful to the tank? Any info would be great. Thanks.


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## AquaticPulse (Jun 19, 2011)

image doesn't seem to load


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## WiyRay (Jan 11, 2009)

Surprisingly... Right click > Open Image in new tab works

Anyway, my guess would be a scud. 

Depending on what you have in your tank, it might be a bad thing (for shrimps and such) or a good thing (such as a tasty snack for a larger fish).


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## ddiaz28 (Jan 8, 2013)

I've got a 29 gallon planted tank with 3 swordtails, 5 cory cats, and 1 Otto.

And thanks for the reply. I googled scuds after I read it and I think you are right. Looks like they shouldn't be a problem. 

Cheers.


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## Fishfur (Mar 4, 2012)

My kuhli loaches seem to like them. If you don't want yours, I'd take them. I'd going to try culturing mine, see how I do with them. They're kind of cute and I get a giggle at the way they mate. One grabs another and rides around on it's back for what seems like hours on end. Looks like a shrimpie rodeo rider.
They are harmless to shrimp and fish, love algae, and don't harm anything unless they are starving, in which case they may eat live plants. But they are detritivores, so prefer algae and dead plant matter and the infusoria they find in the detritus.


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## ddiaz28 (Jan 8, 2013)

Thanks for the reply. Knowing that they are harmless I'll probably just ignore them.


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## Fishfur (Mar 4, 2012)

If you find their numbers are growing higher than you like, let me know. I'll happily take them off your hands.


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## BillD (Jun 5, 2006)

If you want to culture them, I found that thread algae was a great food. I even used them to clean algae off of plants. My culture met it's end after 5 or 6 years when i put a bunch of thread algae containing Rivulus eggs in it into the scud tank. After the killies hatched they made short work of the scuds.


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## Fishfur (Mar 4, 2012)

Dang.. wish I'd known they like hair algae so much.. I'd have given it to them instead of chopping it up for the shrimp.


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## BillD (Jun 5, 2006)

I have never seen it written anywhere in any articles about culturing them to use algae as food. I stumbled on to it, and when i saw what they could do, it was a natural progression to put in algae covered plants such as crypts and Anubias to have them cleaned. Only problem was when the algae was gone they started on the plants. Usually, 24 hours or less they would have the plant cleaned off.


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## Fishfur (Mar 4, 2012)

I have read at least one article that says almost exactly that, might have been on the Skeptical Aquarist, perhaps. I don't have that many of them, because the loaches, I am sure, are eating them. But they manage to survive despite that. I was thinking of giving them their own little tank to see how fast they can reproduce without being eaten. But I'll have a fun time trying to catch a few more to start off a culture. The majority of them were in my QT and I harvested those to sell.
There are some in all the other tanks, but far fewer, and harder to find, as hiding is their main method of survival.


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## ScarletFire (Nov 4, 2012)

Actually, I've read that they're bad for shrimp. They will eat thee plants, not just the algae, and would eat the shrimplets. I remember reading an article where a bunch of shrimp and scuds were put into a breeding box. The remnants were just scuds.


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## Fishfur (Mar 4, 2012)

Yes, Anna was saying today at the shrimp meet that scuds have been seen preying on baby shrimp. Since they are scavengers as well, it's not that surprising - a full grown scud is about 3/8 of an inch long, so it's plenty big enough to prey on newborn shrimplets. I would speculate that the shrimplets would become too big for scuds to take relatively soon, but if you are trying to get as many babies as possible, then I'd skip keeping scuds in their tank. 

The trouble is keeping the scuds out, as they often come hidden in plants. You have to soak them in a bucket at least overnight to have a reasonable chance to make sure any hitchhiking scuds have left new plants. If you put them in a bucket with some rock or a bit of wood on the bottom, any scuds that might be on the plant will drop down to the bottom and hide. That's how I first found out about them, seeing them in a bucket after I'd left new plants in it overnight. At the time I was just too tired to plant them in a tank so the bucket was just a temporary home for them 'til the next day.

But I have not observed any of my scuds eating my plants. They do not seem to bother them, so long as there is other food available that's easier to get at. Because the loaches keep the numbers down, there are probably not enough of them to do much damage anyway. If I were feeding them on purpose, I'd make sure not to put very many in at one time, hoping they'd get eaten before they'd have a chance to breed in the tank.


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