# Ostracod colony, and tank-watching under Magnification.



## Jane in Upton (Aug 10, 2005)

Hi all,

well, I have a 5.5 gallon tank I set up as a shrimp-only tank, heavily planted. I noticed a large ostracod buzzing around early on, and then it seemed to disappear. Well, I now have quite the colony of them going in this tank!

They're really interesting, too! The smaller ones skitter around on the coarse sand grains like boulders, and the larger ones sometimes go for an adventurous swim through open water. 

I've been watching them with a 10x magnifying glass - I can only get a good view of the ones that are within a centimeter or two of the front glass, due to the focus range of my little magnifyer, but its really interesting. There is constant activity between the gravel granules, in the interstitial spaces (haven't used that word in years, LOL!). Some have obviously gorged themselves on algae, as their entire body appears green. 

After watching them under magnification for awhile, its kind of shocking when a snail comes into the field, and looms like a huge godzilla-like creature!

I was thinking of introducting some thread-fin Rainbowfish to this tank, but would that completely eradicate the ostracods? I've been really enjoying watching them. Plus, its kind of neat having "seed shrimp" in with the Neocardinias, who are massive giants by comparison. 

Does anyone know how dense this colony could grow?

Thanks!
-Jane


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## milalic (Aug 26, 2005)

Jane,

Your tanks are full of surprises.
I am not sure how big the colony is or will get.

Reduce their food source - vacuum substrate heavily to get decaying materials out, feed significantly less, remove dead plant leaves if any. Use a fish like a dwarf and see if they eat the ostracods.

Cheers,
Pedro


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## bpm2000 (Jul 5, 2005)

I have a bunch in a plant-only (and snails) 4g as well - freaked out when I saw my first one since I've never seen one before. Endlers and cherries are going in soon so I wonder how long they will last.


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## Jane in Upton (Aug 10, 2005)

Actually, I want to KEEP the ostracods - they're kind of fun to watch!

And, they seem to keep the gravel clean - there's nothing to vacuum up! Also, I have a soil underlayer, so any hard-core gravel vacuuming is not an option.

They seem to be eating the algae off each grain of gravel, and swarm the shrimp poops. There is NO visible mulm in this tank, but I would guess that ostracod droppings are simply not visible to me. I did do a gentle siphoning, and then used a turkey baster to suck up the few biggest ostracods from the wastewater, and return them to the tank. 

I had had some green spot algae on the glass, gravel, and a few plant leaves, but I've been seeing ostracods in the same places - on the glass, gravel and bumbling around on plant leaves, and in the last 2 weeks, the GSA has mostly disappeared! I think their population increase was correlated to the algae, as I'm already seeing a decline in their numbers. Plus, I feed quite sparingly in this tank - 1 Hikari "Crab Cuisine" pellet (they're very small pellets) per 2 shrimp, every other day, with an additional small flake or two of food now and then. 

I don't know why I get such a kick out of these things, but I do. When a larger one occasionally buzzes through mid-water, it reminds me of a bumble bee.

-Jane


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