# Micro-Bugs, not daphnia or cyclops



## davemonkey (Mar 29, 2008)

These are in abundance in my shrimp tank (probably would be a great feast for pygmy sunfish). I looked at them with a 15x lens and they are smooth bodied and more elongated than _Daphnia_ appear to be (unless it's just a different species). My camera would not snap a shot when I tried to focus through the 15x hand lens. (That was irritating because I had a cheaper camera awhile back that would do that for me...grrrrrrr. )

The first pic, I circled two in red. The second pic I tried to draw a blown-up version of what they look like (please excuse my sloppy art). The critter is dead center in the second pic.

They seem to thrive on algae and whatever else is in my _Fissidens_.


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## HeyPK (Jan 23, 2004)

Those look like a large ostracod. If they get numerous, they can damage plants. They are extremely hard to eradicate because they lay eggs that have variable hatching times, up to two years, and are impervious to drying and strong chemicals, such as bleach, acids, etc. Best to have some medium sized fish that eats them.


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## Jeffww (May 25, 2010)

H2O2 can kill them. I had a small break out and I just filled a pipette with H2O2 and hosed them down the same way you would kill algae. I had piles of dead ostracods afterwords and I just used airline hosing and vacuumed them out. You just need to get them before they close their shells.


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## HeyPK (Jan 23, 2004)

But H2O2 can't kill their eggs, and you will all too soon have a new population. Concentrated 100% bleach does not kill their eggs. The only thing I have found that kills the eggs is heat. Heating the tank to 70°C will do it.


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## davemonkey (Mar 29, 2008)

HeyPK said:


> Heating the tank to 70°C will do it.


Hmmm, pretty sure that might stress out the Fissidens. 

Okay, now I know I should never share any plants from this tank...and I think I'll schedule another Pygmy Sunfish hunting trip now that I have a reliable food source for them.

Thanks for the help ID'ing them. Oh, and they aren't as large as the picture makes them look. I zoomed in pretty tight and then cropped the photos to zoom in further. These are barely visible unless you get right up to the tank and look closely.


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## Gordonrichards (Apr 28, 2009)

Yeah, get anything, even a guppy.


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## HeyPK (Jan 23, 2004)

> I zoomed in pretty tight and then cropped the photos to zoom in further. These are barely visible unless you get right up to the tank and look closely.


I could tell by their shape that they are the bad kind. These oval ones seem to really like to munch on Cryptocoryne leaves. There is another, very common, smaller ostracod that is more or less round, rather than oval. These aren't so bad except when they occasionally get very numerous , and then they kill all my snails and eat off all the root hairs on epiphytic plants like water sprite or java fern, causing them to do very poorly. Usually the round ones don't get to such high levels that they are harmful, but the oval ones are worse at lower population levels, and I have made strenuous efforts to get rid of them. They shove their tiny eggs in the little gaps between the silicone and the glass, and the only way I can get an empty tank freed of them is to fill it with water and heat it to around 70° C. 
I once had a crypt that was infested and I tried to get rid of them by keeping the plant floating bare root in a glass jar and changing the water every week, each time thoroughly washing away all ostracods that hatched. The plant kept shedding ostracod babies week after week until I finally gave up six months later. If you have a plant that has ostracod eggs on it, you may have to wait for a year or two before they all hatch.

Apparently these ostracods live in puddles that can dry up and if all the eggs were to hatch after a rain and then the puddle dried up before any of the adults reproduced, that would be the end of the population. This clearly won't happen because of the variable hatching times.

The eggs are practically bomb proof. I tried all kinds of caustic chemicals on them, concentrated nitric acid, concentrated hydrochloric acid, Borax cleaner, concentrated sodium hydroxide and 70% rubbing alcohol. Prolonged anaerobic conditions did not bother them either, nor did prolonged drying. I once had some egg-infested plants, dried them and then composted them in soil for several weeks. I then put the compost in some glass dishes, covered it with a half an inch of gravel and planted some aquatic plants on the surface of the gravel by weighing them down with stones. In about two weeks the ostracods appeared, apparently having burrowed up from the soil through the gravel. They are tough little buggers! I was not really very hopeful that heating them to 70° C would work, but, fortunately it did, or I would have had three 15 gallon tanks with no way of getting them ostracod free.


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## davemonkey (Mar 29, 2008)

Paul, that sounds pretty aweful! My initial thought for now is to let them be fish food. But, it I decide to redo this tank one day with natural soil (I really like the natural soil methods) I'm going to heat my soil in an oven at 250 F, and then do what I can to mimic your tank/water heating at 160 F (I think that is just a hair over 70C ).

This also kinda bums me out because I was going to RAOK alot of the _Fissidens fontanus_ when I move (still up in the air on moving, but a real possibility in the next couple months). That would be a heck of a disclaimer on a freebies! Comes with free indestructible nuisance that can double as fish food!


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## mudboots (Jun 24, 2009)

I can catch a pygmy banded and I'll bring you one on Tuesday. That will at least help you knock out some of the population. Then if you get tired of the fish I'll take it back.


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## Jeffww (May 25, 2010)

I heard larger gouramis will also much on ostracods.


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## HeyPK (Jan 23, 2004)

Dave, you don't have to worry about the ostracods being in soil. The only reason they were in the soil in the example I gave was that I had composted dried plants that had ostracod eggs on them in that soil. That is the only time that the oval ostracods came out of the soil. I have used soil from various places hundreds of times before, and I never had ostracods come out of it.

You could say your Fissidens comes with a plant-munching Ostracod that, short of nuclear bombs, can not be eradicated.

Steven King wrote about them:


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## orisuechris (Aug 14, 2010)

I was under the impression that these were harmless. Am I wrong?


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## HeyPK (Jan 23, 2004)

They are not bad if kept at low numbers, but if they get numerous, they can be bad. See posts above for details.


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## davemonkey (Mar 29, 2008)

+1. Also, there are other micro-bugs that can be really good (like certain _Daphnia sp_. some _Cyclops sp_. ). It's just that this particular species I have in this tank can be a problem if left unchecked.

Ya want some Fissidens?  heeheehee


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## davemonkey (Mar 29, 2008)

Just wanted to update this. I put 3 Pygmy Banded Sunfish in the tank thinking that I had enough Ostracods to feed them regularly. (There were THOUSANDS of them in this tank). After 3 days I could not see any more water bugs (maybe they are just hiding). It has been a few months and I still have yet to see any. The sunfish are still in there and are feeding on baby shrimp and possibly on young ostracods as the old eggs hatch, yet I still have not actually seen any ostracods in there.

-Dave


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## HeyPK (Jan 23, 2004)

After about 3 years you can be pretty sure that all the ostracod eggs have hatched and your tank is now truly free of them!


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## Gordonrichards (Apr 28, 2009)

Lol burn!


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## Tex Gal (Nov 1, 2007)

@heypk What about Potassium permanganate? That's suppose to even penetrate snail shells.


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## HeyPK (Jan 23, 2004)

I have not tried it, but it is an oxidizer like bleach (sodium hypochlorite), but not as powerful. I have tried concentrated bleach, right out of the bottle, and it doesn't touch these eggs! One other thing I have been thinking of trying is acetone. That might get through the egg shells. Rubbing alcohol does not. 

My problem is that, once these ostracods have been in a tank, the tank is forever infested with their eggs. The eggs have delayed hatching times, and it may take years for all of them to hatch. The tank can't be used for growing aquatic plants because they damage the plants as well as get their eggs on the plants. The one solution I have found is to heat the water in the tank up to about 70 degrees centigrade. That kills the eggs. I'll give acetone a try, but I think my best bet is to purchase a 1000 watt bucket heater and rid my two infested 15 gallon tanks and my infested 29 gallon tank of them that way.


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## urbnbtta (Oct 14, 2010)

Are ostracods parthenogenic? I was baffled when I saw the thing zipping around my tank, but I only see one. Is it capable of reproducing on it's own like snails? Do they attack ramshorn snails? Mine is a tiny round one. I think it hitchhiked in on a plant piece my LFS gave with some shrimp. What other plants does it eat? I've had difficulty finding out about them. I'd like to keep it around if it won't do damage to plants, shrimp, snails or guppies.


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## HeyPK (Jan 23, 2004)

Most reproduce sexually, but some are parthenogenetic. Here is a brief page on ostracod biology.


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