I have 2 clowns a bangaii cardinal and a sailfin tang all juveniles and very small all as healthy and happy as can be. I didn't think adding a fish the size of a quarter would add much to the bioload

What is the the tang doing now?
I do not think it is an ammonia problem otherwise you other fish would show problems.

It has to be the transfer or just the shock.
Shut off all the lights on the tank and in the room. Stay away from your tank. It is OK to watch from a distance. Leave the lights in the tank off for a day and observe the fish from a distance. Approach the tank only to feed.

Swimming downwards in one of the branched rocks....constantly swimming and facing down.

ok I'll try it the lights are off now

and dont cut the green wire it will blow everything..

sorry it just sounded like something was going to blow :) i hope it relaxes i had one that did the same thing it was stress regretfully no matter what i did the caribean blue tang didnt make it:( do as he says lights off and leave it be i was so freaked and kept watching checking turning lights on and off flashlight. i now know i made it worse.

well the lights are off in the tank and the room and the power head is near the water line as suggested. Do I turn on the lights to feed? maybe just the actinics?

The fish is stressed so avoid the tank and keep the lights off for 24 hours.
My monkeying around the tank to check its conditions you simply stress the fish more so observe from a distance. The dark tank soothes the fish.
Hope he makes it.

Thanx for the advice and well wishes I'll keep you posted

well he's still alive and has wedged himself in a rock so he wont float up....hopefully he'll be ok.....didn't feed today hopefully that will help