Shark acting funny

[sdexcalibur]

I have a 55 gal tank, It has a oscar, algea eater and a rainbow shark, Now everyone gets along fine, I have a couch shell that I found diving it's been in the tank for a year plus. One day I couldn't find the shark, I looked high and low and could not find him, Finally I moved the shell and their he was, I moved the shell and he always gos back in, We goes way in where it's hard to see hin from the outside,
I don't see any signs of sickness, and like I said everyone gets along fine, Why is he doing this

 

[Ruby Shark]

HI.

Don't worry...this is a common thing for rainbow sharks. It's actually recommended that they have a cave, castle etc. for them to hide in.

 

[astroboy]

THats right.

Rainbow sharks need a "cave" to call their own. Maybe put a pot, fake cave, or driftwood in there.