npt tank with funny lil critters?

Ok i have a 7.5 Gallon desktop tank that back in the beginning of November I decided was my goal to make it look great. So slowly I've added plants and such letting it all grow and trimming it so it will bush out. I am not Using CO2! I currently have 6 Yellow Shrimp and 1 Black Bee Shrimp. Then for Fish I USED to have 2 Peacock Gudgeons in there but they have dissapeared litterally over night, no corpses outside or Inside tank, no trace... So now I decided to wait and see if im just blind no sign. Now there is a Scarlet Badis and a Small Otocinclus.
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Now my Question is...
Should I have Hundreds of Little critters Swimming around my Dwarf Hairgrass that are literally not much bigger than the Periods in this post??
(Image 5 was of where they hang out, Can't see any in picture I don't think, they are light gray and zip around like crazy)

Could be baby shrimp, could be copepods. Do you have a filter? If so, check for your missing fish in there. Stranger things have happened.

where did you buy your yellow shrimp from and how much? thanks

well i did check the filter (which is a little nano red sea filter) and nothing, only my moss growing out the spout.
I got the Yellow shrimp from Aquarium Plus for I think 6 for $25. He has a Great selection of colors also not just yellow or red.
I'm just lost at what they are and wanted to know if i should worry..