What Are These Little Critters In My Tank?!?!

[zaitchev]

I had a pregnant ghost shrimp. I put her in a ten gallon, let her give birth, and then took her out. I fed the little guys but they're dead two weeks later, it would seem, all at the bottom of the tank.

However, running around them are hundreds upon hundreds of these little critters. No larger than the tip of a pin. I can see them with my flashlight. I'm concerned about putting the plant in that tank back in the main tank--what are these things?!?

 

[Chad]

Very well could be Copepods which are common in both fresh and marine tanks. They are little crustaceans which are harmless. However without a video or macro photo I can't say for sure.