Fast moving critter with dragonfly-like body

[PotatoPig]

I noticed this little thing a week or so ago as a larvae about the size of a copepod. It had a body shape like a dragonfly (bumpy larger head area, long straight tail) and was moving around the glass fairly quickly. Today I saw it again, but it’s now a little over 1/8” long, is red - and surprisingly fast for its size.

Couldn’t get a good picture due to its speed, as you’ll see from the video.

Any ideas what this would be - doesn’t seem like a copepod, amphipod or isopod in terms of either build or movement.

 

[Stealthreefer]

My eyes are no longer younger but it kind of looks like an adult brine shrimp or something similar.

 

[WheatToast]

This is a mysid shrimp, which are uncommon, beneficial hitchhikers. They consume algae, detritus, smaller pods, and each other and are preyed upon by larger organisms.