I got a black moore and an oranda 1 week ago (they were in the same tank in the petshop and are the same size) and they were both very lively for the 1st 2 days. The black moore has started lying at the bottom of the tank for most of the day and then returning to normal, swimming around the tank. He is not leaning to the side or upside down and swims normally when I tap the side of the tank. There are no white spots or anything else evident on his body. Any ideas?

Check your water chemistry.  Sounds like it might be a water quality problem to me.

My fish did the same thing when they were in the tank for the first time together. Mind, they always stayed together... resting, swimming, feeding... ANYWAY, i'm not saying it's normal, but it could be stress or anxiety. If you haven't noticed anything odd with the fish, then just give them time and see if they improve. they might also still be getting used to each other's company and the black moore is having issues adjusting.

Thanks for the advice. 2 days ago the black moor developed whitespot, and ironically was more active. I immediately took a sample of water to the petshop who confirmed the ph was fine. They advised me to use a disease medication which treats all kinds of diseases, including white spot, and do partial water changes. The other fish is a fantail and not an oranda as I said previously and it now is covered in white spots. The moor is now back to lying on the bottom of the tank and doesn't look good. The fantail has dark streaks on its tail also. I though it was strange that there were no goldfish at all in the petshop when i went in 9 days after i bought my fish. I guess that the whole lot have been infected. I'm tempted to do a full water change tomorrow to eliminate any waste in the gravel but I'm also reluctant as the stress may be just as damaging!

the white spots are ick you have to treat the whole tank.. you can get the treatment from walmart  or just about anywhere that carries fish but if you do not get rid of it. it will kill your fish and continue to spread.i would no recommend putting any new fish in the tank until you are sure its gone.

Thanks again folks. I started the whitespot treatment 4 days ago when the spots 1st appeared on the black moor. Im afraid it may be too late for these poor wee guys. The moor has been lying at the bottom of the tank for most of the day and the fantail is now gasping for air at the top of the tank and is leaning to the side. I've had goldfish on and off for years and have never came across whitespot before. Here's hoping for a miracle that they'll still be here in the morning.