Ants in tank?

[woodwalker]

I just noticed small little bugs running around on the live rock and
the floor of my fish tank. They are to small to take a pic of, but they look
simillar to ants. Any idea what they can be and if they are harmful??

 

[cranberry]

Sounds like an isopod... but here's the most common variety.
Copepods

Copepod with eggs

Male isopod

Female isopod

Amphipod

 

[texasmetal]

Could also be mysis shrimp.

 

[1knight164]

Try this thread.
https://forums.saltwaterfish.com/t/172998/amphipods-copopods-isopods