Missing Rainbow Shark?

[fish_tank0311]

Hi all.

In my 4 foot tank, i have a rainbow shark, and well you can see below what else i have.

I have not seen my rainbow shark in about 3-4 days, when hes usually hanging around this rock sitting upright in the corner making a cave. He was like a couple inches long, quite new, and i haven't seen him eat. I think in the couple months I've had him I've seen him eat only once or twice. Hes also VERY shy. Hes always sitting in behind the rock in the cave, and hes not sick or whatever. I have seen him out on the odd occasion, but very rarely will he come out. Im wondering if im doing anything wrong, and if there is a way i can kind of lure him out so i can watch him. Im very worried about him, and im really not happy about dead fish in my aquarium, especially if therir only a couple months old.

Thanks For all the help...

 

[WILDER]

Remove tank ornaments and look for him.
Check filter.
Also check floor area around tank.
Do you have any pets.

 

[fish_tank0311]

He wont be in filter, hes far too big for that. Its a 4 foot tank with very large rocks and the back is built up with large rocks reinforcing a hill of pebbles, so i cant really remove all that. Yes i have 3 little dogs, but they pay NO attention to the tank, and he couldnt have jumped out.