It looks like I have grains of sand swimming in my fish tank!!!?

Question

Went to clean my tank today and there are these things swimming all over the tank, they look like grains of sand. I took a sample to Petco and they didn't know what it was. Can anyone help and maybe provide a picture. My fish are doing okay, they have been acting sluggish the last couple of days but no rubbing or anything else.

Answer 1

It could be a few microorganisms, but I'd think ostracods or Daphnia would be the most likely if these swim in a smooth motion. If the "jerk" as they swim, a cyclops would fit this description. If you can use a microscope to see what these look like a little better, compare them to the drawings/photos on these links: http://www.micrographia.com/specbiol/alg/diato/diat0100.htm
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/smal1.html

NOTE: The organisms I'm mentioning are harmless, and your fish may even eat them. If there are a lot of them, it may mean you have a buildup of organic matter in your tank. These are somewhat more common to see in planted tanks, and you may not be cleaning the gravel well enough for fear of disturbing your plants. You might want to do a water test (or take a sample to your pet store) to see if you have high ammonia, nitrite, or nitrate, any of which could explain the behavior of your fish. You should do 25% water changes every week, using a gravel vacuum to remove debris from the gravel.

While ich spends some of its time in the water (not always attached to your fish), you generally wouldn't be able to see these without magnification. And if any time has passed since you've been seeing your "swimmers" if they were parasites, they would have attached to your fish.

Answer 2

These tiny "sands" could be animals, worms quite possibly. If your fish are acting sluggish, then that might be caused by those "sands." I recently 2 guppies from petco. They ended up being sick and infected my whole tank of precious guppies. Those 2 guppies died and now a whole bunch of my prize guppies are infected. I put medicine in there which i had to PAY for even though it was the store's fault for selling infected guppies. Now they are making a profit off of my getting medicine to save what i have left. Those aholes at PETCO! WAAAGH!
One more thing, my tank of guppies also has worms in it, but those worms have never harmed my guppies. My guppies have always been healthy before that damn plague infected my tank. Those worms or whatever you want to call them are beneficial to my tank, eating scraps of food and stuff like that. Think of them like beneficial bacteria, except larger.

Answer 3

http://www.chem-marin.com/cohenapt2.htm
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