Likely a Damselfly nymph. It will predate on fish, so unless you fancy losing some, it would probably be best not to return it to the tank.
There is a nice shortlist of things you might find in a freshwater tank (“What is this thing/bug in my aquarium”) on the right side under FAQs where you can find reference pictures and short descriptions.
You could pop it in another tank and watch it develop into an adult – absolutely fascinating animals.
If you don’t want it please don’t kill it, pop it in a pond so it can make its own way
NF_4 
Likely a Damselfly nymph. It will predate on fish, so unless you fancy losing some, it would probably be best not to return it to the tank.
There is a nice shortlist of things you might find in a freshwater tank (“What is this thing/bug in my aquarium”) on the right side under FAQs where you can find reference pictures and short descriptions.
DONT JUST STAND THERE FCK HIS ASS UP!!
Damselfly nymph, carnivore, will kill everything. Remove ASAP and watch for more
Mayfly larvae! Very pretty. Might eat your cherry shrimp if it’s big enough though. Where do you live?
Edit: more likely a damselfly.
Kill it with fire they are lethal
Kill that thing fast.
Damselfly nymph. Carnivorous and love to eat shrimp, i lost 4 amanos to those blights! Kill on sight
If you live in Michigan I’ll take it, I want those haha
Looks alien bro
Looks cool but is evil
Wtf
You should move to some other state
Put it in a pond if there’s one nearby. It’s beautiful.
Do people not notice when they have dragonfly’s in their homes
Literal deaths
Xenomorph of the shrimp world if im correct
Oh no! What happened to that shrimps swimmerets!?
If it’s local, put it outside in water.
Kill it🤘🏿🤘🏿
Idk but he looks nefarious. I’d say scrap the guy he’s most likely up to no good.
That’s a weird looking cat
You could pop it in another tank and watch it develop into an adult – absolutely fascinating animals.
If you don’t want it please don’t kill it, pop it in a pond so it can make its own way
Behead it!
Behead it!