finally got an octo....but where is he/she?
 

got my octo 3days ago.i know it ate because fish are missing,but i havent seen him since about 1 hour after i put him in.

It's common for them to hide until they are comfortable. You might not see it for days at first. Don't disturb the rocks looking for it, or it will prolong the behavior.

You might try using a dim red light at night to watch the tank and see if it comes out at night. Some octos are nocturnal and never come out during the day, might eventually change habits.

I had the same problem. I'm going to try training mine to eat at the front of the tank so i can see it, as long as yours is eating things are good. Be thankful for that much...