Freshwater Aquarium I̶n̶s̶e̶c̶t̶ Water Mite


I used a syringe to remove a sample of sand substrate from the bottom of my freshwater aquarium. The splotches of granules around the bug are grains of sand. I saw a total of 3 of them from a total of 3 samples. Anyone have any idea what kind of bug it is? I’m guessing it is an insect because of the six legs. I have a video from it if anyone is interested.



It was pointed out that there was a fourth pair of legs hidden away behind the third pair. This being said, likely an aquatic mite, harmless and common in a healthy aquatic system. Thanks Laksiyer for the observations and suggestions. Video can be found via vimeo @



8 Comments Add yours

  1. Manu Prakash says:

    That is a very striking blue patch. Did you apply any stain or this is the original coloration!!


  2. laksiyer says:

    Super nice pic. Looks like a water mite. Note no antennae and if you look carefully, you will see one more pair of legs in the bag. A video of how it moves might reveal more. Could you post it on youtube and you can insert it as a link.

    I like the blue gut. Is it from the methylene blue put into your aquarium or did you try to stain it?

  3. laksiyer says:

    Sorry I meant one more pair of legs behind the third pair. Also aquarium = tank (not a native speaker).

  4. blueram says:

    @Manu, I did not apply any stain. This is the original color and of the number of critters that I found in three samples, they all had coloration just like this. @Laksiyer, good eye on the 4th pair of legs. The video can be seen at

    I didn’t use any methylene blue nor stain it. I’m not sure where the color came from. Kind of strange.

  5. laksiyer says:

    Yes it is a mite. The blue is in the gut, it looks as though it has been ingested and that is why I thought you put MB in tank. Do you have a pH indicator or perhaps some other commercial product (like the sand itself) that you use in your aquarium that might lend the blue… this color does not look natural and you have a Holmes’ian’ mystery at hand. If you figure out the cause please let us know, I want to try it.

  6. Niramay Gogate says:

    I saw your video. Can you tell me how big is this bug? because I have seen similar bug few years ago with a simple microscope.

  7. kbeatty says:

    Did you create a glass slide or a slide from the kit? My wet slides are not turning out how I want them to so I am just trying to understand what I might be doing wrong. Can you post a picture of the wet slide you used to get this picture?

  8. Manu Prakash says:

    @BlueRam This blue color mystery is getting deeper (blue). I searched the catalog for water mites – and although I did not find anything so deep blue, I did find coloration patterns that match the anatomy. So the ingestion theory does hold some water (pun), but again the natural colorations found are also pretty dramatic.

    Also – did you choose your screen name @blueram based on this discovery or do we have a double mystery here 🙂 You should keep a health population of these blue guys, who knows what we have at our hands here..

    Two more resources:

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