Creatures in my tank water 👀 ID help please

[Kassy_]

Greetings.

This morning I noticed something new in my painted turtle's water. At first glance, it appeared to be tiny bubbles. But there were a lot, all throughout the water column. And when I looked closer, they were moving in the current but also moving on their own. Also on the gravel.

Internet searches were exasperating, and my current conclusion is possibly some kind of copepod. However, I'd like to ID the species (if possible) of whatever these creatures are.

Again, the creatures are small and quite circular (mimicking the appearance of small bubbles). They are basically white or transparent, and under my pocket microscope I see grey stripes that start near the center of their back and curve towards the belly. No visible appendages, which seems odd.

I'm going to try to (although I don't think can) attach a few pics and vids. Help would be appreciated. Regardless, I'm embarking on a full tank cleaning because I don't feel comfortable with the population size of these creatures.

I haven't added any new decor in months. I also haven't fed live food in almost as long. So I'm at a loss for how the creatures entered his environment.

 

[Kassy_]

(from later on Dec. 27)
Alright gang, I think all my forum work has gotten me to a pretty solid conclusion:

Cypridopsis vidua.

These "seed shrimp" are ostracods, which are crustaceans. They have basically global distribution.

I'm still completely baffled at how they got in my painted turtle's habitat. I learned their eggs can be dormant for years and years, however I've had my turtle for approximately 4 years, so I'm surprised that "now" was any more of an ideal hatching environment than any other time.

I captured some in two different containers (one with some substrate, one with none) and I want to observe how they do.

I deep-cleaned the entire tank, decor, and substrate. New water is currently settling before I place my turtle back in. I learned the "seed shrimp" are parthnogenic, so those ladies were just going to town, hahaha, which led to the large population I experienced earlier. The deep-clean may not have completely eliminated them (that is yet to be determined) but it certainly has put everything back into proper moderation.

 

[Kassy_]

Well... 18 days later, I'm definitely seeing the "seed shrimp" (Cypridopsis vidua) again. I've officially determined that the deep-clean wasn't sufficient to eliminate the population, but the numbers are (for the time being) acceptable as the "seed shrimp" aren't interested in the turtle whatsoever, just the algae on his log.

After I deep-cleaned, I also cut back on feeding too in hopes of not recreating such an ideal habitat for the "seed shrimp," but seeing as they're back, I may be looking into fish that eat them. My turtle is incredibly inquisitive, so I already know any fish I consider will need ample hiding places.