I purchased 1 Ora ocellaris 2 weeks ago. The lfs said he is 6 months old. I would like to add another clown of the same kind next week. Am I making a mistake in doing this? I will look for the smallest one in the next delivery. An a side question, I have yet to see my clown sleep. Do they ever stop swimming and go lay down somewhere?

i would say they dont lay down somewhere. they always swimming. but when they "sleep" they usually just swim in one area

my clown "sleeps" vertical along side my thermometer!

Providing that its around the same size and species and comes from the same conditions (I wouldn't add a wild with a tank raised for example) I don't think it's a mistake. Be prepared for some fighting while they work things out and keep an eye on them.

There are all sorts of clownfish breeders on N-R christosclowns comes to mind off the top of my head. If you want an "expert" those would be the guys to find.

Fish don't lay down. Some clownfish wiggle non stop. Mine have a corner they go to, they still move, just not as much.

I will be getting the 2nd clown from the same lfs, who gets them from Ora, which are tank raised.

My black and white ocellaris "sleeps" on a rock that has a little nook between another below the powerheads and regular ocellaris sleeps in a cave I made behind some rocks in the back of the tank. I have never seen them just laying there though and are always wiggling. I can easily sit down with a beer and watch my clowns for hours looking at the stuff they do. I have never seen any fish with more personality than clowns.

My clowns like to make a ditch in the corner of my tank every night and just wiggle around in that untill the lights are on again

Yup