mini shrimp like things?

[jtt]

I have a ton of these little critters in my tank, they are hiding in the crevices of the rock, they are pesky little things, fast too. they look like itty bitty shrimp or bugs but with a curled in butt. I unfortunately dont have a camera, but i saw one a few weeks ago, but their population has seemed to grow, and whenever i feed they come out and grab whatever it was i threw in and then runs back into the crevices of the rock to devour them.
ive been looking through what seems like a hundred threads in the hitchhiker part here looking for pics that resemble them but i have been unable. anyone have any ideas? they more or less live under a rock, in the sand or in the rock at the bottom of the tank. and like i said, they kindof resemble some kind of a shrimp but they are teeny tiny, and their butt curls inward.
any help would be appreciated... im getting kindof nervous

 

[cranberry]

Sounds like an amphipod.... gammarid.

 

[jtt]

that is very very close. what are they? they good? bad? should i worry?

 

[cranberry]

They are good and are in most people's tanks. Fish like to eat them. No, don't worry.

 

[mr.clownfish]

or large copepods.
they are even better.

 

[a7xsynx42]

ha. wow, i'm glad you posted this. i just discovered those in my tank too and couldn't find anything about them.. thanks!

 

[jtt]

Hey, so, these things are getting really big... should i be worried?

 

[cranberry]

They can get pretty big. Some peeps say they have seen them pic at corals. I wouldn't be concerned.